feat(third_party/bazel): Check in rules_haskell from Tweag

third_party/bazel/rules_haskell/examples/.bazelrc

@@ -0,0 +1 @@
+../.bazelrc

third_party/bazel/rules_haskell/examples/.gitignore

@@ -0,0 +1 @@
+/bazel-*

third_party/bazel/rules_haskell/examples/BUILD.bazel

@@ -0,0 +1,10 @@
+load(
+    "@io_tweag_rules_haskell//haskell:haskell.bzl",
+    "haskell_toolchain",
+)
+
+haskell_toolchain(
+    name = "ghc",
+    tools = ["@ghc//:bin"],
+    version = "8.6.4",
+)

third_party/bazel/rules_haskell/examples/README.md

@@ -0,0 +1,45 @@
+# rule_haskell examples
+
+Examples of using [rules_haskell][rules_haskell], the Bazel rule set
+for building Haskell code.
+
+* [**vector:**](./vector/) shows how to build the `vector` package as
+  found on Hackage, using a Nix provided compiler toolchain.
+* [**rts:**](./rts/) demonstrates foreign exports and shows how to
+  link against GHC's RTS library, i.e. `libHSrts.so`.
+  
+## **Important**
+
+Run all commands from the root of `rules_haskell`.
+If you `cd examples/`, bazel *will* [break on
+you](https://github.com/tweag/rules_haskell/issues/740).
+This is a current problem with bazel workspaces.
+
+## Root Workspace
+
+Build everything in the root workspace with;
+
+```
+$ bazel build @io_tweag_rules_haskell_examples//...
+```
+
+Show every target of the vector example;
+
+```
+$ bazel query @io_tweag_rules_haskell_examples//vector/...
+@io_tweag_rules_haskell_examples//vector:vector
+@io_tweag_rules_haskell_examples//vector:semigroups
+@io_tweag_rules_haskell_examples//vector:primitive
+@io_tweag_rules_haskell_examples//vector:ghc-prim
+@io_tweag_rules_haskell_examples//vector:deepseq
+@io_tweag_rules_haskell_examples//vector:base
+```
+
+Build the two main Haskell targets;
+
+```
+$ bazel build @io_tweag_rules_haskell_examples//vector
+$ bazel build @io_tweag_rules_haskell_examples//rts:add-one-hs
+```
+
+[rules_haskell]: https://github.com/tweag/rules_haskell

third_party/bazel/rules_haskell/examples/WORKSPACE

@@ -0,0 +1,58 @@
+workspace(name = "io_tweag_rules_haskell_examples")
+
+local_repository(
+    name = "io_tweag_rules_haskell",
+    path = "..",
+)
+
+load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
+load("@io_tweag_rules_haskell//haskell:repositories.bzl", "haskell_repositories")
+
+haskell_repositories()
+
+rules_nixpkgs_version = "0.5.2"
+
+http_archive(
+    name = "io_tweag_rules_nixpkgs",
+    sha256 = "5a384daa57b49abf9f0b672852f1a66a3c52aecf9d4d2ac64f6de0fd307690c8",
+    strip_prefix = "rules_nixpkgs-%s" % rules_nixpkgs_version,
+    urls = ["https://github.com/tweag/rules_nixpkgs/archive/v%s.tar.gz" % rules_nixpkgs_version],
+)
+
+load(
+    "@io_tweag_rules_nixpkgs//nixpkgs:nixpkgs.bzl",
+    "nixpkgs_cc_configure",
+    "nixpkgs_package",
+)
+
+# For the rts example.
+nixpkgs_package(
+    name = "ghc",
+    attribute_path = "haskellPackages.ghc",
+    build_file = "@io_tweag_rules_haskell//haskell:ghc.BUILD",
+    repository = "@io_tweag_rules_haskell//nixpkgs:default.nix",
+)
+
+nixpkgs_cc_configure(
+    nix_file = "@io_tweag_rules_haskell//nixpkgs:cc-toolchain.nix",
+    repository = "@io_tweag_rules_haskell//nixpkgs:default.nix",
+)
+
+load(
+    "@io_tweag_rules_haskell//haskell:nixpkgs.bzl",
+    "haskell_register_ghc_nixpkgs",
+)
+
+haskell_register_ghc_nixpkgs(
+    repositories = {
+        "nixpkgs": "@io_tweag_rules_haskell//nixpkgs:default.nix",
+    },
+    version = "8.6.4",
+)
+
+load(
+    "@io_tweag_rules_haskell//haskell:haskell.bzl",
+    "haskell_register_ghc_bindists",
+)
+
+haskell_register_ghc_bindists(version = "8.6.4")

third_party/bazel/rules_haskell/examples/primitive/BUILD.bazel

@@ -0,0 +1,33 @@
+load(
+    "@io_tweag_rules_haskell//haskell:haskell.bzl",
+    "haskell_cc_import",
+    "haskell_library",
+    "haskell_toolchain_library",
+)
+
+haskell_toolchain_library(name = "base")
+
+haskell_toolchain_library(name = "ghc-prim")
+
+cc_library(
+    name = "memops",
+    srcs = ["cbits/primitive-memops.c"],
+    hdrs = ["cbits/primitive-memops.h"],
+    deps = ["@ghc//:threaded-rts"],
+)
+
+haskell_library(
+    name = "primitive",
+    srcs = glob([
+        "Data/**/*.hs",
+        "Control/**/*.hs",
+    ]),
+    version = "0",
+    visibility = ["//visibility:public"],
+    deps = [
+        ":base",
+        ":ghc-prim",
+        ":memops",
+        "//transformers",
+    ],
+)

third_party/bazel/rules_haskell/examples/primitive/Control/Monad/Primitive.hs

@@ -0,0 +1,298 @@
+{-# LANGUAGE CPP, MagicHash, UnboxedTuples, TypeFamilies #-}
+{-# LANGUAGE FlexibleContexts, FlexibleInstances, UndecidableInstances #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# OPTIONS_GHC -fno-warn-deprecations #-}
+
+-- |
+-- Module      : Control.Monad.Primitive
+-- Copyright   : (c) Roman Leshchinskiy 2009
+-- License     : BSD-style
+--
+-- Maintainer  : Roman Leshchinskiy <rl@cse.unsw.edu.au>
+-- Portability : non-portable
+--
+-- Primitive state-transformer monads
+--
+
+module Control.Monad.Primitive (
+  PrimMonad(..), RealWorld, primitive_,
+  PrimBase(..),
+  liftPrim, primToPrim, primToIO, primToST, ioToPrim, stToPrim,
+  unsafePrimToPrim, unsafePrimToIO, unsafePrimToST, unsafeIOToPrim,
+  unsafeSTToPrim, unsafeInlinePrim, unsafeInlineIO, unsafeInlineST,
+  touch, evalPrim
+) where
+
+import GHC.Prim   ( State#, RealWorld, touch# )
+import GHC.Base   ( unsafeCoerce#, realWorld# )
+#if MIN_VERSION_base(4,4,0)
+import GHC.Base   ( seq# )
+#else
+import Control.Exception (evaluate)
+#endif
+#if MIN_VERSION_base(4,2,0)
+import GHC.IO     ( IO(..) )
+#else
+import GHC.IOBase ( IO(..) )
+#endif
+import GHC.ST     ( ST(..) )
+
+import Control.Monad.Trans.Class (lift)
+#if !MIN_VERSION_base(4,8,0)
+import Data.Monoid (Monoid)
+#endif
+
+import Control.Monad.Trans.Cont     ( ContT    )
+import Control.Monad.Trans.Identity ( IdentityT (IdentityT) )
+import Control.Monad.Trans.List     ( ListT    )
+import Control.Monad.Trans.Maybe    ( MaybeT   )
+import Control.Monad.Trans.Error    ( ErrorT, Error)
+import Control.Monad.Trans.Reader   ( ReaderT  )
+import Control.Monad.Trans.State    ( StateT   )
+import Control.Monad.Trans.Writer   ( WriterT  )
+import Control.Monad.Trans.RWS      ( RWST     )
+
+#if MIN_VERSION_transformers(0,4,0)
+import Control.Monad.Trans.Except   ( ExceptT  )
+#endif
+
+#if MIN_VERSION_transformers(0,5,3)
+import Control.Monad.Trans.Accum    ( AccumT   )
+import Control.Monad.Trans.Select   ( SelectT  )
+#endif
+
+import qualified Control.Monad.Trans.RWS.Strict    as Strict ( RWST   )
+import qualified Control.Monad.Trans.State.Strict  as Strict ( StateT )
+import qualified Control.Monad.Trans.Writer.Strict as Strict ( WriterT )
+
+-- | Class of monads which can perform primitive state-transformer actions
+class Monad m => PrimMonad m where
+  -- | State token type
+  type PrimState m
+
+  -- | Execute a primitive operation
+  primitive :: (State# (PrimState m) -> (# State# (PrimState m), a #)) -> m a
+
+-- | Class of primitive monads for state-transformer actions.
+--
+-- Unlike 'PrimMonad', this typeclass requires that the @Monad@ be fully
+-- expressed as a state transformer, therefore disallowing other monad
+-- transformers on top of the base @IO@ or @ST@.
+--
+-- @since 0.6.0.0
+class PrimMonad m => PrimBase m where
+  -- | Expose the internal structure of the monad
+  internal :: m a -> State# (PrimState m) -> (# State# (PrimState m), a #)
+
+-- | Execute a primitive operation with no result
+primitive_ :: PrimMonad m
+              => (State# (PrimState m) -> State# (PrimState m)) -> m ()
+{-# INLINE primitive_ #-}
+primitive_ f = primitive (\s# ->
+    case f s# of
+        s'# -> (# s'#, () #))
+
+instance PrimMonad IO where
+  type PrimState IO = RealWorld
+  primitive = IO
+  {-# INLINE primitive #-}
+instance PrimBase IO where
+  internal (IO p) = p
+  {-# INLINE internal #-}
+
+-- | @since 0.6.3.0
+instance PrimMonad m => PrimMonad (ContT r m) where
+  type PrimState (ContT r m) = PrimState m
+  primitive = lift . primitive
+  {-# INLINE primitive #-}
+
+instance PrimMonad m => PrimMonad (IdentityT m) where
+  type PrimState (IdentityT m) = PrimState m
+  primitive = lift . primitive
+  {-# INLINE primitive #-}
+
+-- | @since 0.6.2.0
+instance PrimBase m => PrimBase (IdentityT m) where
+  internal (IdentityT m) = internal m
+  {-# INLINE internal #-}
+
+instance PrimMonad m => PrimMonad (ListT m) where
+  type PrimState (ListT m) = PrimState m
+  primitive = lift . primitive
+  {-# INLINE primitive #-}
+
+instance PrimMonad m => PrimMonad (MaybeT m) where
+  type PrimState (MaybeT m) = PrimState m
+  primitive = lift . primitive
+  {-# INLINE primitive #-}
+
+instance (Error e, PrimMonad m) => PrimMonad (ErrorT e m) where
+  type PrimState (ErrorT e m) = PrimState m
+  primitive = lift . primitive
+  {-# INLINE primitive #-}
+
+instance PrimMonad m => PrimMonad (ReaderT r m) where
+  type PrimState (ReaderT r m) = PrimState m
+  primitive = lift . primitive
+  {-# INLINE primitive #-}
+
+instance PrimMonad m => PrimMonad (StateT s m) where
+  type PrimState (StateT s m) = PrimState m
+  primitive = lift . primitive
+  {-# INLINE primitive #-}
+
+instance (Monoid w, PrimMonad m) => PrimMonad (WriterT w m) where
+  type PrimState (WriterT w m) = PrimState m
+  primitive = lift . primitive
+  {-# INLINE primitive #-}
+
+instance (Monoid w, PrimMonad m) => PrimMonad (RWST r w s m) where
+  type PrimState (RWST r w s m) = PrimState m
+  primitive = lift . primitive
+  {-# INLINE primitive #-}
+
+#if MIN_VERSION_transformers(0,4,0)
+instance PrimMonad m => PrimMonad (ExceptT e m) where
+  type PrimState (ExceptT e m) = PrimState m
+  primitive = lift . primitive
+  {-# INLINE primitive #-}
+#endif
+
+#if MIN_VERSION_transformers(0,5,3)
+-- | @since 0.6.3.0
+instance ( Monoid w
+         , PrimMonad m
+# if !(MIN_VERSION_base(4,8,0))
+         , Functor m
+# endif
+         ) => PrimMonad (AccumT w m) where
+  type PrimState (AccumT w m) = PrimState m
+  primitive = lift . primitive
+  {-# INLINE primitive #-}
+instance PrimMonad m => PrimMonad (SelectT r m) where
+  type PrimState (SelectT r m) = PrimState m
+  primitive = lift . primitive
+  {-# INLINE primitive #-}
+#endif
+
+instance PrimMonad m => PrimMonad (Strict.StateT s m) where
+  type PrimState (Strict.StateT s m) = PrimState m
+  primitive = lift . primitive
+  {-# INLINE primitive #-}
+
+instance (Monoid w, PrimMonad m) => PrimMonad (Strict.WriterT w m) where
+  type PrimState (Strict.WriterT w m) = PrimState m
+  primitive = lift . primitive
+  {-# INLINE primitive #-}
+
+instance (Monoid w, PrimMonad m) => PrimMonad (Strict.RWST r w s m) where
+  type PrimState (Strict.RWST r w s m) = PrimState m
+  primitive = lift . primitive
+  {-# INLINE primitive #-}
+
+instance PrimMonad (ST s) where
+  type PrimState (ST s) = s
+  primitive = ST
+  {-# INLINE primitive #-}
+instance PrimBase (ST s) where
+  internal (ST p) = p
+  {-# INLINE internal #-}
+
+-- | Lifts a 'PrimBase' into another 'PrimMonad' with the same underlying state
+-- token type.
+liftPrim
+  :: (PrimBase m1, PrimMonad m2, PrimState m1 ~ PrimState m2) => m1 a -> m2 a
+{-# INLINE liftPrim #-}
+liftPrim = primToPrim
+
+-- | Convert a 'PrimBase' to another monad with the same state token.
+primToPrim :: (PrimBase m1, PrimMonad m2, PrimState m1 ~ PrimState m2)
+        => m1 a -> m2 a
+{-# INLINE primToPrim #-}
+primToPrim m = primitive (internal m)
+
+-- | Convert a 'PrimBase' with a 'RealWorld' state token to 'IO'
+primToIO :: (PrimBase m, PrimState m ~ RealWorld) => m a -> IO a
+{-# INLINE primToIO #-}
+primToIO = primToPrim
+
+-- | Convert a 'PrimBase' to 'ST'
+primToST :: PrimBase m => m a -> ST (PrimState m) a
+{-# INLINE primToST #-}
+primToST = primToPrim
+
+-- | Convert an 'IO' action to a 'PrimMonad'.
+-- 
+-- @since 0.6.2.0
+ioToPrim :: (PrimMonad m, PrimState m ~ RealWorld) => IO a -> m a
+{-# INLINE ioToPrim #-}
+ioToPrim = primToPrim
+
+-- | Convert an 'ST' action to a 'PrimMonad'.
+--
+-- @since 0.6.2.0
+stToPrim :: PrimMonad m => ST (PrimState m) a -> m a
+{-# INLINE stToPrim #-}
+stToPrim = primToPrim
+
+-- | Convert a 'PrimBase' to another monad with a possibly different state
+-- token. This operation is highly unsafe!
+unsafePrimToPrim :: (PrimBase m1, PrimMonad m2) => m1 a -> m2 a
+{-# INLINE unsafePrimToPrim #-}
+unsafePrimToPrim m = primitive (unsafeCoerce# (internal m))
+
+-- | Convert any 'PrimBase' to 'ST' with an arbitrary state token. This
+-- operation is highly unsafe!
+unsafePrimToST :: PrimBase m => m a -> ST s a
+{-# INLINE unsafePrimToST #-}
+unsafePrimToST = unsafePrimToPrim
+
+-- | Convert any 'PrimBase' to 'IO'. This operation is highly unsafe!
+unsafePrimToIO :: PrimBase m => m a -> IO a
+{-# INLINE unsafePrimToIO #-}
+unsafePrimToIO = unsafePrimToPrim
+
+-- | Convert an 'ST' action with an arbitraty state token to any 'PrimMonad'.
+-- This operation is highly unsafe!
+-- 
+-- @since 0.6.2.0
+unsafeSTToPrim :: PrimMonad m => ST s a -> m a
+{-# INLINE unsafeSTToPrim #-}
+unsafeSTToPrim = unsafePrimToPrim
+
+-- | Convert an 'IO' action to any 'PrimMonad'. This operation is highly
+-- unsafe!
+--
+-- @since 0.6.2.0
+unsafeIOToPrim :: PrimMonad m => IO a -> m a
+{-# INLINE unsafeIOToPrim #-}
+unsafeIOToPrim = unsafePrimToPrim
+
+unsafeInlinePrim :: PrimBase m => m a -> a
+{-# INLINE unsafeInlinePrim #-}
+unsafeInlinePrim m = unsafeInlineIO (unsafePrimToIO m)
+
+unsafeInlineIO :: IO a -> a
+{-# INLINE unsafeInlineIO #-}
+unsafeInlineIO m = case internal m realWorld# of (# _, r #) -> r
+
+unsafeInlineST :: ST s a -> a
+{-# INLINE unsafeInlineST #-}
+unsafeInlineST = unsafeInlinePrim
+
+touch :: PrimMonad m => a -> m ()
+{-# INLINE touch #-}
+touch x = unsafePrimToPrim
+        $ (primitive (\s -> case touch# x s of { s' -> (# s', () #) }) :: IO ())
+
+-- | Create an action to force a value; generalizes 'Control.Exception.evaluate'
+--
+-- @since 0.6.2.0
+evalPrim :: forall a m . PrimMonad m => a -> m a
+#if MIN_VERSION_base(4,4,0)
+evalPrim a = primitive (\s -> seq# a s)
+#else
+-- This may or may not work so well, but there's probably nothing better to do.
+{-# NOINLINE evalPrim #-}
+evalPrim a = unsafePrimToPrim (evaluate a :: IO a)
+#endif

third_party/bazel/rules_haskell/examples/primitive/Data/Primitive.hs

@@ -0,0 +1,85 @@
+{-# LANGUAGE MagicHash #-}
+{-# OPTIONS_GHC -fno-warn-duplicate-exports #-}
+-- |
+-- Module      : Data.Primitive
+-- Copyright   : (c) Roman Leshchinskiy 2009-2012
+-- License     : BSD-style
+--
+-- Maintainer  : Roman Leshchinskiy <rl@cse.unsw.edu.au>
+-- Portability : non-portable
+--
+-- Reexports all primitive operations
+--
+module Data.Primitive (
+  -- * Re-exports
+  module Data.Primitive.Types
+  ,module Data.Primitive.Array
+  ,module Data.Primitive.ByteArray
+  ,module Data.Primitive.Addr
+  ,module Data.Primitive.SmallArray
+  ,module Data.Primitive.UnliftedArray
+  ,module Data.Primitive.PrimArray
+  ,module Data.Primitive.MutVar
+  -- * Naming Conventions
+  -- $namingConventions
+) where
+
+import Data.Primitive.Types
+import Data.Primitive.Array
+import Data.Primitive.ByteArray
+import Data.Primitive.Addr
+import Data.Primitive.SmallArray
+import Data.Primitive.UnliftedArray
+import Data.Primitive.PrimArray
+import Data.Primitive.MutVar
+
+{- $namingConventions
+For historical reasons, this library embraces the practice of suffixing
+the name of a function with the type it operates on. For example, three
+of the variants of the array indexing function are:
+
+> indexArray      ::           Array      a -> Int -> a
+> indexSmallArray ::           SmallArray a -> Int -> a
+> indexPrimArray  :: Prim a => PrimArray  a -> Int -> a
+
+In a few places, where the language sounds more natural, the array type
+is instead used as a prefix. For example, @Data.Primitive.SmallArray@
+exports @smallArrayFromList@, which would sound unnatural if it used
+@SmallArray@ as a suffix instead.
+
+This library provides several functions traversing, building, and filtering
+arrays. These functions are suffixed with an additional character to
+indicate their the nature of their effectfulness:
+
+* No suffix: A non-effectful pass over the array.
+* @-A@ suffix: An effectful pass over the array, where the effect is 'Applicative'.
+* @-P@ suffix: An effectful pass over the array, where the effect is 'PrimMonad'.
+
+Additionally, an apostrophe can be used to indicate strictness in the elements.
+The variants with an apostrophe are used in @Data.Primitive.Array@ but not
+in @Data.Primitive.PrimArray@ since the array type it provides is always strict in the element.
+For example, there are three variants of the function that filters elements
+from a primitive array.
+
+> filterPrimArray  :: (Prim a               ) => (a ->   Bool) -> PrimArray a ->    PrimArray a
+> filterPrimArrayA :: (Prim a, Applicative f) => (a -> f Bool) -> PrimArray a -> f (PrimArray a)
+> filterPrimArrayP :: (Prim a, PrimMonad   m) => (a -> m Bool) -> PrimArray a -> m (PrimArray a)
+
+As long as the effectful context is a monad that is sufficiently affine
+the behaviors of the 'Applicative' and 'PrimMonad' variants produce the same results
+and differ only in their strictness. Monads that are sufficiently affine
+include:
+
+* 'IO' and 'ST'
+* Any combination of 'MaybeT', 'ExceptT', 'StateT' and 'Writer' on top
+  of another sufficiently affine monad.
+
+There is one situation where the names deviate from effectful suffix convention
+described above. Throughout the haskell ecosystem, the 'Applicative' variant of
+'map' is known as 'traverse', not @mapA@. Consequently, we adopt the following
+naming convention for mapping:
+
+> mapPrimArray :: (Prim a, Prim b) => (a -> b) -> PrimArray a -> PrimArray b
+> traversePrimArray :: (Applicative f, Prim a, Prim b) => (a -> f b) -> PrimArray a -> f (PrimArray b)
+> traversePrimArrayP :: (PrimMonad m, Prim a, Prim b) => (a -> m b) -> PrimArray a -> m (PrimArray b)
+-}

third_party/bazel/rules_haskell/examples/primitive/Data/Primitive/Addr.hs

@@ -0,0 +1,133 @@
+{-# LANGUAGE MagicHash, UnboxedTuples, CPP #-}
+
+-- |
+-- Module      : Data.Primitive.Addr
+-- Copyright   : (c) Roman Leshchinskiy 2009-2012
+-- License     : BSD-style
+--
+-- Maintainer  : Roman Leshchinskiy <rl@cse.unsw.edu.au>
+-- Portability : non-portable
+--
+-- Primitive operations on machine addresses
+--
+
+module Data.Primitive.Addr (
+  -- * Types
+  Addr(..),
+
+  -- * Address arithmetic
+  nullAddr, plusAddr, minusAddr, remAddr,
+
+  -- * Element access
+  indexOffAddr, readOffAddr, writeOffAddr,
+
+  -- * Block operations
+  copyAddr,
+#if __GLASGOW_HASKELL__ >= 708
+  copyAddrToByteArray,
+#endif
+  moveAddr, setAddr,
+
+  -- * Conversion
+  addrToInt
+) where
+
+import Control.Monad.Primitive
+import Data.Primitive.Types
+#if __GLASGOW_HASKELL__ >= 708
+import Data.Primitive.ByteArray
+#endif
+
+import GHC.Base ( Int(..) )
+import GHC.Prim
+
+import GHC.Ptr
+import Foreign.Marshal.Utils
+
+
+-- | The null address
+nullAddr :: Addr
+nullAddr = Addr nullAddr#
+
+infixl 6 `plusAddr`, `minusAddr`
+infixl 7 `remAddr`
+
+-- | Offset an address by the given number of bytes
+plusAddr :: Addr -> Int -> Addr
+plusAddr (Addr a#) (I# i#) = Addr (plusAddr# a# i#)
+
+-- | Distance in bytes between two addresses. The result is only valid if the
+-- difference fits in an 'Int'.
+minusAddr :: Addr -> Addr -> Int
+minusAddr (Addr a#) (Addr b#) = I# (minusAddr# a# b#)
+
+-- | The remainder of the address and the integer.
+remAddr :: Addr -> Int -> Int
+remAddr (Addr a#) (I# i#) = I# (remAddr# a# i#)
+
+-- | Read a value from a memory position given by an address and an offset.
+-- The memory block the address refers to must be immutable. The offset is in
+-- elements of type @a@ rather than in bytes.
+indexOffAddr :: Prim a => Addr -> Int -> a
+{-# INLINE indexOffAddr #-}
+indexOffAddr (Addr addr#) (I# i#) = indexOffAddr# addr# i#
+
+-- | Read a value from a memory position given by an address and an offset.
+-- The offset is in elements of type @a@ rather than in bytes.
+readOffAddr :: (Prim a, PrimMonad m) => Addr -> Int -> m a
+{-# INLINE readOffAddr #-}
+readOffAddr (Addr addr#) (I# i#) = primitive (readOffAddr# addr# i#)
+
+-- | Write a value to a memory position given by an address and an offset.
+-- The offset is in elements of type @a@ rather than in bytes.
+writeOffAddr :: (Prim a, PrimMonad m) => Addr -> Int -> a -> m ()
+{-# INLINE writeOffAddr #-}
+writeOffAddr (Addr addr#) (I# i#) x = primitive_ (writeOffAddr# addr# i# x)
+
+-- | Copy the given number of bytes from the second 'Addr' to the first. The
+-- areas may not overlap.
+copyAddr :: PrimMonad m => Addr         -- ^ destination address
+                        -> Addr         -- ^ source address
+                        -> Int          -- ^ number of bytes
+                        -> m ()
+{-# INLINE copyAddr #-}
+copyAddr (Addr dst#) (Addr src#) n
+  = unsafePrimToPrim $ copyBytes (Ptr dst#) (Ptr src#) n
+
+#if __GLASGOW_HASKELL__ >= 708
+-- | Copy the given number of bytes from the 'Addr' to the 'MutableByteArray'.
+--   The areas may not overlap. This function is only available when compiling
+--   with GHC 7.8 or newer.
+--   
+--   @since 0.6.4.0
+copyAddrToByteArray :: PrimMonad m
+  => MutableByteArray (PrimState m) -- ^ destination
+  -> Int -- ^ offset into the destination array
+  -> Addr -- ^ source
+  -> Int -- ^ number of bytes to copy
+  -> m ()
+{-# INLINE copyAddrToByteArray #-}
+copyAddrToByteArray (MutableByteArray marr) (I# off) (Addr addr) (I# len) =
+  primitive_ $ copyAddrToByteArray# addr marr off len
+#endif
+
+-- | Copy the given number of bytes from the second 'Addr' to the first. The
+-- areas may overlap.
+moveAddr :: PrimMonad m => Addr         -- ^ destination address
+                        -> Addr         -- ^ source address
+                        -> Int          -- ^ number of bytes
+                        -> m ()
+{-# INLINE moveAddr #-}
+moveAddr (Addr dst#) (Addr src#) n
+  = unsafePrimToPrim $ moveBytes (Ptr dst#) (Ptr src#) n
+
+-- | Fill a memory block of with the given value. The length is in
+-- elements of type @a@ rather than in bytes.
+setAddr :: (Prim a, PrimMonad m) => Addr -> Int -> a -> m ()
+{-# INLINE setAddr #-}
+setAddr (Addr addr#) (I# n#) x = primitive_ (setOffAddr# addr# 0# n# x)
+
+-- | Convert an 'Addr' to an 'Int'.
+addrToInt :: Addr -> Int
+{-# INLINE addrToInt #-}
+addrToInt (Addr addr#) = I# (addr2Int# addr#)

third_party/bazel/rules_haskell/examples/primitive/Data/Primitive/Array.hs

@@ -0,0 +1,822 @@
+{-# LANGUAGE CPP, MagicHash, UnboxedTuples, DeriveDataTypeable, BangPatterns #-}
+{-# LANGUAGE RankNTypes #-}
+{-# LANGUAGE TypeFamilies #-}
+
+-- |
+-- Module      : Data.Primitive.Array
+-- Copyright   : (c) Roman Leshchinskiy 2009-2012
+-- License     : BSD-style
+--
+-- Maintainer  : Roman Leshchinskiy <rl@cse.unsw.edu.au>
+-- Portability : non-portable
+--
+-- Primitive arrays of boxed values.
+--
+
+module Data.Primitive.Array (
+  Array(..), MutableArray(..),
+
+  newArray, readArray, writeArray, indexArray, indexArrayM, indexArray##,
+  freezeArray, thawArray, runArray,
+  unsafeFreezeArray, unsafeThawArray, sameMutableArray,
+  copyArray, copyMutableArray,
+  cloneArray, cloneMutableArray,
+  sizeofArray, sizeofMutableArray,
+  fromListN, fromList,
+  mapArray',
+  traverseArrayP
+) where
+
+import Control.Monad.Primitive
+
+import GHC.Base  ( Int(..) )
+import GHC.Prim
+import qualified GHC.Exts as Exts
+#if (MIN_VERSION_base(4,7,0))
+import GHC.Exts (fromListN, fromList)
+#endif
+
+import Data.Typeable ( Typeable )
+import Data.Data
+  (Data(..), DataType, mkDataType, Constr, mkConstr, Fixity(..), constrIndex)
+import Data.Primitive.Internal.Compat ( isTrue#, mkNoRepType )
+
+import Control.Monad.ST(ST,runST)
+
+import Control.Applicative
+import Control.Monad (MonadPlus(..), when)
+import Control.Monad.Fix
+#if MIN_VERSION_base(4,4,0)
+import Control.Monad.Zip
+#endif
+import Data.Foldable (Foldable(..), toList)
+#if !(MIN_VERSION_base(4,8,0))
+import Data.Traversable (Traversable(..))
+import Data.Monoid
+#endif
+#if MIN_VERSION_base(4,9,0)
+import qualified GHC.ST as GHCST
+import qualified Data.Foldable as F
+import Data.Semigroup
+#endif
+#if MIN_VERSION_base(4,8,0)
+import Data.Functor.Identity
+#endif
+#if MIN_VERSION_base(4,10,0)
+import GHC.Exts (runRW#)
+#elif MIN_VERSION_base(4,9,0)
+import GHC.Base (runRW#)
+#endif
+
+import Text.ParserCombinators.ReadP
+
+#if MIN_VERSION_base(4,9,0) || MIN_VERSION_transformers(0,4,0)
+import Data.Functor.Classes (Eq1(..),Ord1(..),Show1(..),Read1(..))
+#endif
+
+-- | Boxed arrays
+data Array a = Array
+  { array# :: Array# a }
+  deriving ( Typeable )
+
+-- | Mutable boxed arrays associated with a primitive state token.
+data MutableArray s a = MutableArray
+  { marray# :: MutableArray# s a }
+  deriving ( Typeable )
+
+sizeofArray :: Array a -> Int
+sizeofArray a = I# (sizeofArray# (array# a))
+{-# INLINE sizeofArray #-}
+
+sizeofMutableArray :: MutableArray s a -> Int
+sizeofMutableArray a = I# (sizeofMutableArray# (marray# a))
+{-# INLINE sizeofMutableArray #-}
+
+-- | Create a new mutable array of the specified size and initialise all
+-- elements with the given value.
+newArray :: PrimMonad m => Int -> a -> m (MutableArray (PrimState m) a)
+{-# INLINE newArray #-}
+newArray (I# n#) x = primitive
+   (\s# -> case newArray# n# x s# of
+             (# s'#, arr# #) ->
+               let ma = MutableArray arr#
+               in (# s'# , ma #))
+
+-- | Read a value from the array at the given index.
+readArray :: PrimMonad m => MutableArray (PrimState m) a -> Int -> m a
+{-# INLINE readArray #-}
+readArray arr (I# i#) = primitive (readArray# (marray# arr) i#)
+
+-- | Write a value to the array at the given index.
+writeArray :: PrimMonad m => MutableArray (PrimState m) a -> Int -> a -> m ()
+{-# INLINE writeArray #-}
+writeArray arr (I# i#) x = primitive_ (writeArray# (marray# arr) i# x)
+
+-- | Read a value from the immutable array at the given index.
+indexArray :: Array a -> Int -> a
+{-# INLINE indexArray #-}
+indexArray arr (I# i#) = case indexArray# (array# arr) i# of (# x #) -> x
+
+-- | Read a value from the immutable array at the given index, returning
+-- the result in an unboxed unary tuple. This is currently used to implement
+-- folds.
+indexArray## :: Array a -> Int -> (# a #)
+indexArray## arr (I# i) = indexArray# (array# arr) i
+{-# INLINE indexArray## #-}
+
+-- | Monadically read a value from the immutable array at the given index.
+-- This allows us to be strict in the array while remaining lazy in the read
+-- element which is very useful for collective operations. Suppose we want to
+-- copy an array. We could do something like this:
+--
+-- > copy marr arr ... = do ...
+-- >                        writeArray marr i (indexArray arr i) ...
+-- >                        ...
+--
+-- But since primitive arrays are lazy, the calls to 'indexArray' will not be
+-- evaluated. Rather, @marr@ will be filled with thunks each of which would
+-- retain a reference to @arr@. This is definitely not what we want!
+--
+-- With 'indexArrayM', we can instead write
+--
+-- > copy marr arr ... = do ...
+-- >                        x <- indexArrayM arr i
+-- >                        writeArray marr i x
+-- >                        ...
+--
+-- Now, indexing is executed immediately although the returned element is
+-- still not evaluated.
+--
+indexArrayM :: Monad m => Array a -> Int -> m a
+{-# INLINE indexArrayM #-}
+indexArrayM arr (I# i#)
+  = case indexArray# (array# arr) i# of (# x #) -> return x
+
+-- | Create an immutable copy of a slice of an array.
+--
+-- This operation makes a copy of the specified section, so it is safe to
+-- continue using the mutable array afterward.
+freezeArray
+  :: PrimMonad m
+  => MutableArray (PrimState m) a -- ^ source
+  -> Int                          -- ^ offset
+  -> Int                          -- ^ length
+  -> m (Array a)
+{-# INLINE freezeArray #-}
+freezeArray (MutableArray ma#) (I# off#) (I# len#) =
+  primitive $ \s -> case freezeArray# ma# off# len# s of
+    (# s', a# #) -> (# s', Array a# #)
+
+-- | Convert a mutable array to an immutable one without copying. The
+-- array should not be modified after the conversion.
+unsafeFreezeArray :: PrimMonad m => MutableArray (PrimState m) a -> m (Array a)
+{-# INLINE unsafeFreezeArray #-}
+unsafeFreezeArray arr
+  = primitive (\s# -> case unsafeFreezeArray# (marray# arr) s# of
+                        (# s'#, arr'# #) ->
+                          let a = Array arr'#
+                          in (# s'#, a #))
+
+-- | Create a mutable array from a slice of an immutable array.
+--
+-- This operation makes a copy of the specified slice, so it is safe to use the
+-- immutable array afterward.
+thawArray
+  :: PrimMonad m
+  => Array a -- ^ source
+  -> Int     -- ^ offset
+  -> Int     -- ^ length
+  -> m (MutableArray (PrimState m) a)
+{-# INLINE thawArray #-}
+thawArray (Array a#) (I# off#) (I# len#) =
+  primitive $ \s -> case thawArray# a# off# len# s of
+    (# s', ma# #) -> (# s', MutableArray ma# #)
+
+-- | Convert an immutable array to an mutable one without copying. The
+-- immutable array should not be used after the conversion.
+unsafeThawArray :: PrimMonad m => Array a -> m (MutableArray (PrimState m) a)
+{-# INLINE unsafeThawArray #-}
+unsafeThawArray a
+  = primitive (\s# -> case unsafeThawArray# (array# a) s# of
+                        (# s'#, arr'# #) ->
+                          let ma = MutableArray arr'#
+                          in (# s'#, ma #))
+
+-- | Check whether the two arrays refer to the same memory block.
+sameMutableArray :: MutableArray s a -> MutableArray s a -> Bool
+{-# INLINE sameMutableArray #-}
+sameMutableArray arr brr
+  = isTrue# (sameMutableArray# (marray# arr) (marray# brr))
+
+-- | Copy a slice of an immutable array to a mutable array.
+copyArray :: PrimMonad m
+          => MutableArray (PrimState m) a    -- ^ destination array
+          -> Int                             -- ^ offset into destination array
+          -> Array a                         -- ^ source array
+          -> Int                             -- ^ offset into source array
+          -> Int                             -- ^ number of elements to copy
+          -> m ()
+{-# INLINE copyArray #-}
+#if __GLASGOW_HASKELL__ > 706
+-- NOTE: copyArray# and copyMutableArray# are slightly broken in GHC 7.6.* and earlier
+copyArray (MutableArray dst#) (I# doff#) (Array src#) (I# soff#) (I# len#)
+  = primitive_ (copyArray# src# soff# dst# doff# len#)
+#else
+copyArray !dst !doff !src !soff !len = go 0
+  where
+    go i | i < len = do
+                       x <- indexArrayM src (soff+i)
+                       writeArray dst (doff+i) x
+                       go (i+1)
+         | otherwise = return ()
+#endif
+
+-- | Copy a slice of a mutable array to another array. The two arrays may
+-- not be the same.
+copyMutableArray :: PrimMonad m
+          => MutableArray (PrimState m) a    -- ^ destination array
+          -> Int                             -- ^ offset into destination array
+          -> MutableArray (PrimState m) a    -- ^ source array
+          -> Int                             -- ^ offset into source array
+          -> Int                             -- ^ number of elements to copy
+          -> m ()
+{-# INLINE copyMutableArray #-}
+#if __GLASGOW_HASKELL__ >= 706
+-- NOTE: copyArray# and copyMutableArray# are slightly broken in GHC 7.6.* and earlier
+copyMutableArray (MutableArray dst#) (I# doff#)
+                 (MutableArray src#) (I# soff#) (I# len#)
+  = primitive_ (copyMutableArray# src# soff# dst# doff# len#)
+#else
+copyMutableArray !dst !doff !src !soff !len = go 0
+  where
+    go i | i < len = do
+                       x <- readArray src (soff+i)
+                       writeArray dst (doff+i) x
+                       go (i+1)
+         | otherwise = return ()
+#endif
+
+-- | Return a newly allocated Array with the specified subrange of the
+-- provided Array. The provided Array should contain the full subrange
+-- specified by the two Ints, but this is not checked.
+cloneArray :: Array a -- ^ source array
+           -> Int     -- ^ offset into destination array
+           -> Int     -- ^ number of elements to copy
+           -> Array a
+{-# INLINE cloneArray #-}
+cloneArray (Array arr#) (I# off#) (I# len#)
+  = case cloneArray# arr# off# len# of arr'# -> Array arr'#
+
+-- | Return a newly allocated MutableArray. with the specified subrange of
+-- the provided MutableArray. The provided MutableArray should contain the
+-- full subrange specified by the two Ints, but this is not checked.
+cloneMutableArray :: PrimMonad m
+        => MutableArray (PrimState m) a -- ^ source array
+        -> Int                          -- ^ offset into destination array
+        -> Int                          -- ^ number of elements to copy
+        -> m (MutableArray (PrimState m) a)
+{-# INLINE cloneMutableArray #-}
+cloneMutableArray (MutableArray arr#) (I# off#) (I# len#) = primitive
+   (\s# -> case cloneMutableArray# arr# off# len# s# of
+             (# s'#, arr'# #) -> (# s'#, MutableArray arr'# #))
+
+emptyArray :: Array a
+emptyArray =
+  runST $ newArray 0 (die "emptyArray" "impossible") >>= unsafeFreezeArray
+{-# NOINLINE emptyArray #-}
+
+#if !MIN_VERSION_base(4,9,0)
+createArray
+  :: Int
+  -> a
+  -> (forall s. MutableArray s a -> ST s ())
+  -> Array a
+createArray 0 _ _ = emptyArray
+createArray n x f = runArray $ do
+  mary <- newArray n x
+  f mary
+  pure mary
+
+runArray
+  :: (forall s. ST s (MutableArray s a))
+  -> Array a
+runArray m = runST $ m >>= unsafeFreezeArray
+
+#else /* Below, runRW# is available. */
+
+-- This low-level business is designed to work with GHC's worker-wrapper
+-- transformation. A lot of the time, we don't actually need an Array
+-- constructor. By putting it on the outside, and being careful about
+-- how we special-case the empty array, we can make GHC smarter about this.
+-- The only downside is that separately created 0-length arrays won't share
+-- their Array constructors, although they'll share their underlying
+-- Array#s.
+createArray
+  :: Int
+  -> a
+  -> (forall s. MutableArray s a -> ST s ())
+  -> Array a
+createArray 0 _ _ = Array (emptyArray# (# #))
+createArray n x f = runArray $ do
+  mary <- newArray n x
+  f mary
+  pure mary
+
+runArray
+  :: (forall s. ST s (MutableArray s a))
+  -> Array a
+runArray m = Array (runArray# m)
+
+runArray#
+  :: (forall s. ST s (MutableArray s a))
+  -> Array# a
+runArray# m = case runRW# $ \s ->
+  case unST m s of { (# s', MutableArray mary# #) ->
+  unsafeFreezeArray# mary# s'} of (# _, ary# #) -> ary#
+
+unST :: ST s a -> State# s -> (# State# s, a #)
+unST (GHCST.ST f) = f
+
+emptyArray# :: (# #) -> Array# a
+emptyArray# _ = case emptyArray of Array ar -> ar
+{-# NOINLINE emptyArray# #-}
+#endif
+
+
+die :: String -> String -> a
+die fun problem = error $ "Data.Primitive.Array." ++ fun ++ ": " ++ problem
+
+arrayLiftEq :: (a -> b -> Bool) -> Array a -> Array b -> Bool
+arrayLiftEq p a1 a2 = sizeofArray a1 == sizeofArray a2 && loop (sizeofArray a1 - 1)
+  where loop i | i < 0     = True
+               | (# x1 #) <- indexArray## a1 i
+               , (# x2 #) <- indexArray## a2 i
+               , otherwise = p x1 x2 && loop (i-1)
+
+instance Eq a => Eq (Array a) where
+  a1 == a2 = arrayLiftEq (==) a1 a2
+
+#if MIN_VERSION_base(4,9,0) || MIN_VERSION_transformers(0,4,0)
+-- | @since 0.6.4.0
+instance Eq1 Array where
+#if MIN_VERSION_base(4,9,0) || MIN_VERSION_transformers(0,5,0)
+  liftEq = arrayLiftEq
+#else
+  eq1 = arrayLiftEq (==)
+#endif
+#endif
+
+instance Eq (MutableArray s a) where
+  ma1 == ma2 = isTrue# (sameMutableArray# (marray# ma1) (marray# ma2))
+
+arrayLiftCompare :: (a -> b -> Ordering) -> Array a -> Array b -> Ordering
+arrayLiftCompare elemCompare a1 a2 = loop 0
+  where
+  mn = sizeofArray a1 `min` sizeofArray a2
+  loop i
+    | i < mn
+    , (# x1 #) <- indexArray## a1 i
+    , (# x2 #) <- indexArray## a2 i
+    = elemCompare x1 x2 `mappend` loop (i+1)
+    | otherwise = compare (sizeofArray a1) (sizeofArray a2)
+
+-- | Lexicographic ordering. Subject to change between major versions.
+instance Ord a => Ord (Array a) where
+  compare a1 a2 = arrayLiftCompare compare a1 a2
+
+#if MIN_VERSION_base(4,9,0) || MIN_VERSION_transformers(0,4,0)
+-- | @since 0.6.4.0
+instance Ord1 Array where
+#if MIN_VERSION_base(4,9,0) || MIN_VERSION_transformers(0,5,0)
+  liftCompare = arrayLiftCompare
+#else
+  compare1 = arrayLiftCompare compare
+#endif
+#endif
+
+instance Foldable Array where
+  -- Note: we perform the array lookups eagerly so we won't
+  -- create thunks to perform lookups even if GHC can't see
+  -- that the folding function is strict.
+  foldr f = \z !ary ->
+    let
+      !sz = sizeofArray ary
+      go i
+        | i == sz = z
+        | (# x #) <- indexArray## ary i
+        = f x (go (i+1))
+    in go 0
+  {-# INLINE foldr #-}
+  foldl f = \z !ary ->
+    let
+      go i
+        | i < 0 = z
+        | (# x #) <- indexArray## ary i
+        = f (go (i-1)) x
+    in go (sizeofArray ary - 1)
+  {-# INLINE foldl #-}
+  foldr1 f = \ !ary ->
+    let
+      !sz = sizeofArray ary - 1
+      go i =
+        case indexArray## ary i of
+          (# x #) | i == sz -> x
+                  | otherwise -> f x (go (i+1))
+    in if sz < 0
+       then die "foldr1" "empty array"
+       else go 0
+  {-# INLINE foldr1 #-}
+  foldl1 f = \ !ary ->
+    let
+      !sz = sizeofArray ary - 1
+      go i =
+        case indexArray## ary i of
+          (# x #) | i == 0 -> x
+                  | otherwise -> f (go (i - 1)) x
+    in if sz < 0
+       then die "foldl1" "empty array"
+       else go sz
+  {-# INLINE foldl1 #-}
+#if MIN_VERSION_base(4,6,0)
+  foldr' f = \z !ary ->
+    let
+      go i !acc
+        | i == -1 = acc
+        | (# x #) <- indexArray## ary i
+        = go (i-1) (f x acc)
+    in go (sizeofArray ary - 1) z
+  {-# INLINE foldr' #-}
+  foldl' f = \z !ary ->
+    let
+      !sz = sizeofArray ary
+      go i !acc
+        | i == sz = acc
+        | (# x #) <- indexArray## ary i
+        = go (i+1) (f acc x)
+    in go 0 z
+  {-# INLINE foldl' #-}
+#endif
+#if MIN_VERSION_base(4,8,0)
+  null a = sizeofArray a == 0
+  {-# INLINE null #-}
+  length = sizeofArray
+  {-# INLINE length #-}
+  maximum ary | sz == 0   = die "maximum" "empty array"
+              | (# frst #) <- indexArray## ary 0
+              = go 1 frst
+   where
+     sz = sizeofArray ary
+     go i !e
+       | i == sz = e
+       | (# x #) <- indexArray## ary i
+       = go (i+1) (max e x)
+  {-# INLINE maximum #-}
+  minimum ary | sz == 0   = die "minimum" "empty array"
+              | (# frst #) <- indexArray## ary 0
+              = go 1 frst
+   where sz = sizeofArray ary
+         go i !e
+           | i == sz = e
+           | (# x #) <- indexArray## ary i
+           = go (i+1) (min e x)
+  {-# INLINE minimum #-}
+  sum = foldl' (+) 0
+  {-# INLINE sum #-}
+  product = foldl' (*) 1
+  {-# INLINE product #-}
+#endif
+
+newtype STA a = STA {_runSTA :: forall s. MutableArray# s a -> ST s (Array a)}
+
+runSTA :: Int -> STA a -> Array a
+runSTA !sz = \ (STA m) -> runST $ newArray_ sz >>= \ ar -> m (marray# ar)
+{-# INLINE runSTA #-}
+
+newArray_ :: Int -> ST s (MutableArray s a)
+newArray_ !n = newArray n badTraverseValue
+
+badTraverseValue :: a
+badTraverseValue = die "traverse" "bad indexing"
+{-# NOINLINE badTraverseValue #-}
+
+instance Traversable Array where
+  traverse f = traverseArray f
+  {-# INLINE traverse #-}
+
+traverseArray
+  :: Applicative f
+  => (a -> f b)
+  -> Array a
+  -> f (Array b)
+traverseArray f = \ !ary ->
+  let
+    !len = sizeofArray ary
+    go !i
+      | i == len = pure $ STA $ \mary -> unsafeFreezeArray (MutableArray mary)
+      | (# x #) <- indexArray## ary i
+      = liftA2 (\b (STA m) -> STA $ \mary ->
+                  writeArray (MutableArray mary) i b >> m mary)
+               (f x) (go (i + 1))
+  in if len == 0
+     then pure emptyArray
+     else runSTA len <$> go 0
+{-# INLINE [1] traverseArray #-}
+
+{-# RULES
+"traverse/ST" forall (f :: a -> ST s b). traverseArray f =
+   traverseArrayP f
+"traverse/IO" forall (f :: a -> IO b). traverseArray f =
+   traverseArrayP f
+ #-}
+#if MIN_VERSION_base(4,8,0)
+{-# RULES
+"traverse/Id" forall (f :: a -> Identity b). traverseArray f =
+   (coerce :: (Array a -> Array (Identity b))
+           -> Array a -> Identity (Array b)) (fmap f)
+ #-}
+#endif
+
+-- | This is the fastest, most straightforward way to traverse
+-- an array, but it only works correctly with a sufficiently
+-- "affine" 'PrimMonad' instance. In particular, it must only produce
+-- *one* result array. 'Control.Monad.Trans.List.ListT'-transformed
+-- monads, for example, will not work right at all.
+traverseArrayP
+  :: PrimMonad m
+  => (a -> m b)
+  -> Array a
+  -> m (Array b)
+traverseArrayP f = \ !ary ->
+  let
+    !sz = sizeofArray ary
+    go !i !mary
+      | i == sz
+      = unsafeFreezeArray mary
+      | otherwise
+      = do
+          a <- indexArrayM ary i
+          b <- f a
+          writeArray mary i b
+          go (i + 1) mary
+  in do
+    mary <- newArray sz badTraverseValue
+    go 0 mary
+{-# INLINE traverseArrayP #-}
+
+-- | Strict map over the elements of the array.
+mapArray' :: (a -> b) -> Array a -> Array b
+mapArray' f a =
+  createArray (sizeofArray a) (die "mapArray'" "impossible") $ \mb ->
+    let go i | i == sizeofArray a
+             = return ()
+             | otherwise
+             = do x <- indexArrayM a i
+                  -- We use indexArrayM here so that we will perform the
+                  -- indexing eagerly even if f is lazy.
+                  let !y = f x
+                  writeArray mb i y >> go (i+1)
+     in go 0
+{-# INLINE mapArray' #-}
+
+arrayFromListN :: Int -> [a] -> Array a
+arrayFromListN n l =
+  createArray n (die "fromListN" "uninitialized element") $ \sma ->
+    let go !ix [] = if ix == n
+          then return ()
+          else die "fromListN" "list length less than specified size"
+        go !ix (x : xs) = if ix < n
+          then do
+            writeArray sma ix x
+            go (ix+1) xs
+          else die "fromListN" "list length greater than specified size"
+    in go 0 l
+
+arrayFromList :: [a] -> Array a
+arrayFromList l = arrayFromListN (length l) l
+
+#if MIN_VERSION_base(4,7,0)
+instance Exts.IsList (Array a) where
+  type Item (Array a) = a
+  fromListN = arrayFromListN
+  fromList = arrayFromList
+  toList = toList
+#else
+fromListN :: Int -> [a] -> Array a
+fromListN = arrayFromListN
+
+fromList :: [a] -> Array a
+fromList = arrayFromList
+#endif
+
+instance Functor Array where
+  fmap f a =
+    createArray (sizeofArray a) (die "fmap" "impossible") $ \mb ->
+      let go i | i == sizeofArray a
+               = return ()
+               | otherwise
+               = do x <- indexArrayM a i
+                    writeArray mb i (f x) >> go (i+1)
+       in go 0
+#if MIN_VERSION_base(4,8,0)
+  e <$ a = createArray (sizeofArray a) e (\ !_ -> pure ())
+#endif
+
+instance Applicative Array where
+  pure x = runArray $ newArray 1 x
+  ab <*> a = createArray (szab*sza) (die "<*>" "impossible") $ \mb ->
+    let go1 i = when (i < szab) $
+            do
+              f <- indexArrayM ab i
+              go2 (i*sza) f 0
+              go1 (i+1)
+        go2 off f j = when (j < sza) $
+            do
+              x <- indexArrayM a j
+              writeArray mb (off + j) (f x)
+              go2 off f (j + 1)
+    in go1 0
+   where szab = sizeofArray ab ; sza = sizeofArray a
+  a *> b = createArray (sza*szb) (die "*>" "impossible") $ \mb ->
+    let go i | i < sza   = copyArray mb (i * szb) b 0 szb
+             | otherwise = return ()
+     in go 0
+   where sza = sizeofArray a ; szb = sizeofArray b
+  a <* b = createArray (sza*szb) (die "<*" "impossible") $ \ma ->
+    let fill off i e | i < szb   = writeArray ma (off+i) e >> fill off (i+1) e
+                     | otherwise = return ()
+        go i | i < sza
+             = do x <- indexArrayM a i
+                  fill (i*szb) 0 x >> go (i+1)
+             | otherwise = return ()
+     in go 0
+   where sza = sizeofArray a ; szb = sizeofArray b
+
+instance Alternative Array where
+  empty = emptyArray
+  a1 <|> a2 = createArray (sza1 + sza2) (die "<|>" "impossible") $ \ma ->
+    copyArray ma 0 a1 0 sza1 >> copyArray ma sza1 a2 0 sza2
+   where sza1 = sizeofArray a1 ; sza2 = sizeofArray a2
+  some a | sizeofArray a == 0 = emptyArray
+         | otherwise = die "some" "infinite arrays are not well defined"
+  many a | sizeofArray a == 0 = pure []
+         | otherwise = die "many" "infinite arrays are not well defined"
+
+data ArrayStack a
+  = PushArray !(Array a) !(ArrayStack a)
+  | EmptyStack
+-- See the note in SmallArray about how we might improve this.
+
+instance Monad Array where
+  return = pure
+  (>>) = (*>)
+
+  ary >>= f = collect 0 EmptyStack (la-1)
+   where
+   la = sizeofArray ary
+   collect sz stk i
+     | i < 0 = createArray sz (die ">>=" "impossible") $ fill 0 stk
+     | (# x #) <- indexArray## ary i
+     , let sb = f x
+           lsb = sizeofArray sb
+       -- If we don't perform this check, we could end up allocating
+       -- a stack full of empty arrays if someone is filtering most
+       -- things out. So we refrain from pushing empty arrays.
+     = if lsb == 0
+       then collect sz stk (i - 1)
+       else collect (sz + lsb) (PushArray sb stk) (i-1)
+
+   fill _   EmptyStack         _   = return ()
+   fill off (PushArray sb sbs) smb
+     | let lsb = sizeofArray sb
+     = copyArray smb off sb 0 (lsb)
+         *> fill (off + lsb) sbs smb
+
+  fail _ = empty
+
+instance MonadPlus Array where
+  mzero = empty
+  mplus = (<|>)
+
+zipW :: String -> (a -> b -> c) -> Array a -> Array b -> Array c
+zipW s f aa ab = createArray mn (die s "impossible") $ \mc ->
+  let go i | i < mn
+           = do
+               x <- indexArrayM aa i
+               y <- indexArrayM ab i
+               writeArray mc i (f x y)
+               go (i+1)
+           | otherwise = return ()
+   in go 0
+ where mn = sizeofArray aa `min` sizeofArray ab
+{-# INLINE zipW #-}
+
+#if MIN_VERSION_base(4,4,0)
+instance MonadZip Array where
+  mzip aa ab = zipW "mzip" (,) aa ab
+  mzipWith f aa ab = zipW "mzipWith" f aa ab
+  munzip aab = runST $ do
+    let sz = sizeofArray aab
+    ma <- newArray sz (die "munzip" "impossible")
+    mb <- newArray sz (die "munzip" "impossible")
+    let go i | i < sz = do
+          (a, b) <- indexArrayM aab i
+          writeArray ma i a
+          writeArray mb i b
+          go (i+1)
+        go _ = return ()
+    go 0
+    (,) <$> unsafeFreezeArray ma <*> unsafeFreezeArray mb
+#endif
+
+instance MonadFix Array where
+  mfix f = createArray (sizeofArray (f err))
+                       (die "mfix" "impossible") $ flip fix 0 $
+    \r !i !mary -> when (i < sz) $ do
+                      writeArray mary i (fix (\xi -> f xi `indexArray` i))
+                      r (i + 1) mary
+    where
+      sz = sizeofArray (f err)
+      err = error "mfix for Data.Primitive.Array applied to strict function."
+
+#if MIN_VERSION_base(4,9,0)
+-- | @since 0.6.3.0
+instance Semigroup (Array a) where
+  (<>) = (<|>)
+  sconcat = mconcat . F.toList
+#endif
+
+instance Monoid (Array a) where
+  mempty = empty
+#if !(MIN_VERSION_base(4,11,0))
+  mappend = (<|>)
+#endif
+  mconcat l = createArray sz (die "mconcat" "impossible") $ \ma ->
+    let go !_  [    ] = return ()
+        go off (a:as) =
+          copyArray ma off a 0 (sizeofArray a) >> go (off + sizeofArray a) as
+     in go 0 l
+   where sz = sum . fmap sizeofArray $ l
+
+arrayLiftShowsPrec :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> Int -> Array a -> ShowS
+arrayLiftShowsPrec elemShowsPrec elemListShowsPrec p a = showParen (p > 10) $
+  showString "fromListN " . shows (sizeofArray a) . showString " "
+    . listLiftShowsPrec elemShowsPrec elemListShowsPrec 11 (toList a)
+
+-- this need to be included for older ghcs
+listLiftShowsPrec :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> Int -> [a] -> ShowS
+listLiftShowsPrec _ sl _ = sl
+
+instance Show a => Show (Array a) where
+  showsPrec p a = arrayLiftShowsPrec showsPrec showList p a
+
+#if MIN_VERSION_base(4,9,0) || MIN_VERSION_transformers(0,4,0)
+-- | @since 0.6.4.0
+instance Show1 Array where
+#if MIN_VERSION_base(4,9,0) || MIN_VERSION_transformers(0,5,0)
+  liftShowsPrec = arrayLiftShowsPrec
+#else
+  showsPrec1 = arrayLiftShowsPrec showsPrec showList
+#endif
+#endif
+
+arrayLiftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (Array a)
+arrayLiftReadsPrec _ listReadsPrec p = readParen (p > 10) . readP_to_S $ do
+  () <$ string "fromListN"
+  skipSpaces
+  n <- readS_to_P reads
+  skipSpaces
+  l <- readS_to_P listReadsPrec
+  return $ arrayFromListN n l
+
+instance Read a => Read (Array a) where
+  readsPrec = arrayLiftReadsPrec readsPrec readList
+
+#if MIN_VERSION_base(4,9,0) || MIN_VERSION_transformers(0,4,0)
+-- | @since 0.6.4.0
+instance Read1 Array where
+#if MIN_VERSION_base(4,9,0) || MIN_VERSION_transformers(0,5,0)
+  liftReadsPrec = arrayLiftReadsPrec
+#else
+  readsPrec1 = arrayLiftReadsPrec readsPrec readList
+#endif
+#endif
+
+
+arrayDataType :: DataType
+arrayDataType = mkDataType "Data.Primitive.Array.Array" [fromListConstr]
+
+fromListConstr :: Constr
+fromListConstr = mkConstr arrayDataType "fromList" [] Prefix
+
+instance Data a => Data (Array a) where
+  toConstr _ = fromListConstr
+  dataTypeOf _ = arrayDataType
+  gunfold k z c = case constrIndex c of
+    1 -> k (z fromList)
+    _ -> error "gunfold"
+  gfoldl f z m = z fromList `f` toList m
+
+instance (Typeable s, Typeable a) => Data (MutableArray s a) where
+  toConstr _ = error "toConstr"
+  gunfold _ _ = error "gunfold"
+  dataTypeOf _ = mkNoRepType "Data.Primitive.Array.MutableArray"

third_party/bazel/rules_haskell/examples/primitive/Data/Primitive/ByteArray.hs

@@ -0,0 +1,549 @@
+{-# LANGUAGE BangPatterns, CPP, MagicHash, UnboxedTuples, UnliftedFFITypes, DeriveDataTypeable #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE TypeFamilies #-}
+
+-- |
+-- Module      : Data.Primitive.ByteArray
+-- Copyright   : (c) Roman Leshchinskiy 2009-2012
+-- License     : BSD-style
+--
+-- Maintainer  : Roman Leshchinskiy <rl@cse.unsw.edu.au>
+-- Portability : non-portable
+--
+-- Primitive operations on ByteArrays
+--
+
+module Data.Primitive.ByteArray (
+  -- * Types
+  ByteArray(..), MutableByteArray(..), ByteArray#, MutableByteArray#,
+
+  -- * Allocation
+  newByteArray, newPinnedByteArray, newAlignedPinnedByteArray,
+  resizeMutableByteArray,
+
+  -- * Element access
+  readByteArray, writeByteArray, indexByteArray,
+
+  -- * Constructing
+  byteArrayFromList, byteArrayFromListN,
+
+  -- * Folding
+  foldrByteArray,
+
+  -- * Freezing and thawing
+  unsafeFreezeByteArray, unsafeThawByteArray,
+
+  -- * Block operations
+  copyByteArray, copyMutableByteArray,
+#if __GLASGOW_HASKELL__ >= 708
+  copyByteArrayToAddr, copyMutableByteArrayToAddr,
+#endif
+  moveByteArray,
+  setByteArray, fillByteArray,
+
+  -- * Information
+  sizeofByteArray,
+  sizeofMutableByteArray, getSizeofMutableByteArray, sameMutableByteArray,
+#if __GLASGOW_HASKELL__ >= 802
+  isByteArrayPinned, isMutableByteArrayPinned,
+#endif
+  byteArrayContents, mutableByteArrayContents
+
+) where
+
+import Control.Monad.Primitive
+import Control.Monad.ST
+import Data.Primitive.Types
+
+import Foreign.C.Types
+import Data.Word ( Word8 )
+import GHC.Base ( Int(..) )
+#if __GLASGOW_HASKELL__ >= 708
+import qualified GHC.Exts as Exts ( IsList(..) )
+#endif
+import GHC.Prim
+#if __GLASGOW_HASKELL__ >= 706
+    hiding (setByteArray#)
+#endif
+
+import Data.Typeable ( Typeable )
+import Data.Data ( Data(..) )
+import Data.Primitive.Internal.Compat ( isTrue#, mkNoRepType )
+import Numeric
+
+#if MIN_VERSION_base(4,9,0)
+import qualified Data.Semigroup as SG
+import qualified Data.Foldable as F
+#endif
+
+#if !(MIN_VERSION_base(4,8,0))
+import Data.Monoid (Monoid(..))
+#endif
+
+#if __GLASGOW_HASKELL__ >= 802
+import GHC.Exts as Exts (isByteArrayPinned#,isMutableByteArrayPinned#)
+#endif
+
+#if __GLASGOW_HASKELL__ >= 804
+import GHC.Exts (compareByteArrays#)
+#else
+import System.IO.Unsafe (unsafeDupablePerformIO)
+#endif
+
+-- | Byte arrays
+data ByteArray = ByteArray ByteArray# deriving ( Typeable )
+
+-- | Mutable byte arrays associated with a primitive state token
+data MutableByteArray s = MutableByteArray (MutableByteArray# s)
+                                        deriving( Typeable )
+
+-- | Create a new mutable byte array of the specified size in bytes.
+newByteArray :: PrimMonad m => Int -> m (MutableByteArray (PrimState m))
+{-# INLINE newByteArray #-}
+newByteArray (I# n#)
+  = primitive (\s# -> case newByteArray# n# s# of
+                        (# s'#, arr# #) -> (# s'#, MutableByteArray arr# #))
+
+-- | Create a /pinned/ byte array of the specified size in bytes. The garbage
+-- collector is guaranteed not to move it.
+newPinnedByteArray :: PrimMonad m => Int -> m (MutableByteArray (PrimState m))
+{-# INLINE newPinnedByteArray #-}
+newPinnedByteArray (I# n#)
+  = primitive (\s# -> case newPinnedByteArray# n# s# of
+                        (# s'#, arr# #) -> (# s'#, MutableByteArray arr# #))
+
+-- | Create a /pinned/ byte array of the specified size in bytes and with the
+-- given alignment. The garbage collector is guaranteed not to move it.
+newAlignedPinnedByteArray
+  :: PrimMonad m
+  => Int  -- ^ size
+  -> Int  -- ^ alignment
+  -> m (MutableByteArray (PrimState m))
+{-# INLINE newAlignedPinnedByteArray #-}
+newAlignedPinnedByteArray (I# n#) (I# k#)
+  = primitive (\s# -> case newAlignedPinnedByteArray# n# k# s# of
+                        (# s'#, arr# #) -> (# s'#, MutableByteArray arr# #))
+
+-- | Yield a pointer to the array's data. This operation is only safe on
+-- /pinned/ byte arrays allocated by 'newPinnedByteArray' or
+-- 'newAlignedPinnedByteArray'.
+byteArrayContents :: ByteArray -> Addr
+{-# INLINE byteArrayContents #-}
+byteArrayContents (ByteArray arr#) = Addr (byteArrayContents# arr#)
+
+-- | Yield a pointer to the array's data. This operation is only safe on
+-- /pinned/ byte arrays allocated by 'newPinnedByteArray' or
+-- 'newAlignedPinnedByteArray'.
+mutableByteArrayContents :: MutableByteArray s -> Addr
+{-# INLINE mutableByteArrayContents #-}
+mutableByteArrayContents (MutableByteArray arr#)
+  = Addr (byteArrayContents# (unsafeCoerce# arr#))
+
+-- | Check if the two arrays refer to the same memory block.
+sameMutableByteArray :: MutableByteArray s -> MutableByteArray s -> Bool
+{-# INLINE sameMutableByteArray #-}
+sameMutableByteArray (MutableByteArray arr#) (MutableByteArray brr#)
+  = isTrue# (sameMutableByteArray# arr# brr#)
+
+-- | Resize a mutable byte array. The new size is given in bytes.
+--
+-- This will either resize the array in-place or, if not possible, allocate the
+-- contents into a new, unpinned array and copy the original array's contents.
+--
+-- To avoid undefined behaviour, the original 'MutableByteArray' shall not be
+-- accessed anymore after a 'resizeMutableByteArray' has been performed.
+-- Moreover, no reference to the old one should be kept in order to allow
+-- garbage collection of the original 'MutableByteArray' in case a new
+-- 'MutableByteArray' had to be allocated.
+--
+-- @since 0.6.4.0
+resizeMutableByteArray
+  :: PrimMonad m => MutableByteArray (PrimState m) -> Int
+                 -> m (MutableByteArray (PrimState m))
+{-# INLINE resizeMutableByteArray #-}
+#if __GLASGOW_HASKELL__ >= 710
+resizeMutableByteArray (MutableByteArray arr#) (I# n#)
+  = primitive (\s# -> case resizeMutableByteArray# arr# n# s# of
+                        (# s'#, arr'# #) -> (# s'#, MutableByteArray arr'# #))
+#else
+resizeMutableByteArray arr n
+  = do arr' <- newByteArray n
+       copyMutableByteArray arr' 0 arr 0 (min (sizeofMutableByteArray arr) n)
+       return arr'
+#endif
+
+-- | Get the size of a byte array in bytes. Unlike 'sizeofMutableByteArray',
+-- this function ensures sequencing in the presence of resizing.
+getSizeofMutableByteArray
+  :: PrimMonad m => MutableByteArray (PrimState m) -> m Int
+{-# INLINE getSizeofMutableByteArray #-}
+#if __GLASGOW_HASKELL__ >= 801
+getSizeofMutableByteArray (MutableByteArray arr#)
+  = primitive (\s# -> case getSizeofMutableByteArray# arr# s# of
+                        (# s'#, n# #) -> (# s'#, I# n# #))
+#else
+getSizeofMutableByteArray arr
+  = return (sizeofMutableByteArray arr)
+#endif
+
+-- | Convert a mutable byte array to an immutable one without copying. The
+-- array should not be modified after the conversion.
+unsafeFreezeByteArray
+  :: PrimMonad m => MutableByteArray (PrimState m) -> m ByteArray
+{-# INLINE unsafeFreezeByteArray #-}
+unsafeFreezeByteArray (MutableByteArray arr#)
+  = primitive (\s# -> case unsafeFreezeByteArray# arr# s# of
+                        (# s'#, arr'# #) -> (# s'#, ByteArray arr'# #))
+
+-- | Convert an immutable byte array to a mutable one without copying. The
+-- original array should not be used after the conversion.
+unsafeThawByteArray
+  :: PrimMonad m => ByteArray -> m (MutableByteArray (PrimState m))
+{-# INLINE unsafeThawByteArray #-}
+unsafeThawByteArray (ByteArray arr#)
+  = primitive (\s# -> (# s#, MutableByteArray (unsafeCoerce# arr#) #))
+
+-- | Size of the byte array in bytes.
+sizeofByteArray :: ByteArray -> Int
+{-# INLINE sizeofByteArray #-}
+sizeofByteArray (ByteArray arr#) = I# (sizeofByteArray# arr#)
+
+-- | Size of the mutable byte array in bytes. This function\'s behavior 
+-- is undefined if 'resizeMutableByteArray' is ever called on the mutable
+-- byte array given as the argument. Consequently, use of this function
+-- is discouraged. Prefer 'getSizeofMutableByteArray', which ensures correct
+-- sequencing in the presence of resizing.
+sizeofMutableByteArray :: MutableByteArray s -> Int
+{-# INLINE sizeofMutableByteArray #-}
+sizeofMutableByteArray (MutableByteArray arr#) = I# (sizeofMutableByteArray# arr#)
+
+#if __GLASGOW_HASKELL__ >= 802
+-- | Check whether or not the byte array is pinned. Pinned byte arrays cannot
+--   be moved by the garbage collector. It is safe to use 'byteArrayContents'
+--   on such byte arrays. This function is only available when compiling with
+--   GHC 8.2 or newer.
+--
+--   @since 0.6.4.0
+isByteArrayPinned :: ByteArray -> Bool
+{-# INLINE isByteArrayPinned #-}
+isByteArrayPinned (ByteArray arr#) = isTrue# (Exts.isByteArrayPinned# arr#)
+
+-- | Check whether or not the mutable byte array is pinned. This function is
+--   only available when compiling with GHC 8.2 or newer.
+--
+--   @since 0.6.4.0
+isMutableByteArrayPinned :: MutableByteArray s -> Bool
+{-# INLINE isMutableByteArrayPinned #-}
+isMutableByteArrayPinned (MutableByteArray marr#) = isTrue# (Exts.isMutableByteArrayPinned# marr#)
+#endif
+
+-- | Read a primitive value from the byte array. The offset is given in
+-- elements of type @a@ rather than in bytes.
+indexByteArray :: Prim a => ByteArray -> Int -> a
+{-# INLINE indexByteArray #-}
+indexByteArray (ByteArray arr#) (I# i#) = indexByteArray# arr# i#
+
+-- | Read a primitive value from the byte array. The offset is given in
+-- elements of type @a@ rather than in bytes.
+readByteArray
+  :: (Prim a, PrimMonad m) => MutableByteArray (PrimState m) -> Int -> m a
+{-# INLINE readByteArray #-}
+readByteArray (MutableByteArray arr#) (I# i#)
+  = primitive (readByteArray# arr# i#)
+
+-- | Write a primitive value to the byte array. The offset is given in
+-- elements of type @a@ rather than in bytes.
+writeByteArray
+  :: (Prim a, PrimMonad m) => MutableByteArray (PrimState m) -> Int -> a -> m ()
+{-# INLINE writeByteArray #-}
+writeByteArray (MutableByteArray arr#) (I# i#) x
+  = primitive_ (writeByteArray# arr# i# x)
+
+-- | Right-fold over the elements of a 'ByteArray'.
+foldrByteArray :: forall a b. (Prim a) => (a -> b -> b) -> b -> ByteArray -> b
+foldrByteArray f z arr = go 0
+  where
+    go i
+      | sizeofByteArray arr > i * sz = f (indexByteArray arr i) (go (i+1))
+      | otherwise                    = z
+    sz = sizeOf (undefined :: a)
+
+byteArrayFromList :: Prim a => [a] -> ByteArray
+byteArrayFromList xs = byteArrayFromListN (length xs) xs
+
+byteArrayFromListN :: Prim a => Int -> [a] -> ByteArray
+byteArrayFromListN n ys = runST $ do
+    marr <- newByteArray (n * sizeOf (head ys))
+    let go !ix [] = if ix == n
+          then return ()
+          else die "byteArrayFromListN" "list length less than specified size"
+        go !ix (x : xs) = if ix < n
+          then do
+            writeByteArray marr ix x
+            go (ix + 1) xs
+          else die "byteArrayFromListN" "list length greater than specified size"
+    go 0 ys
+    unsafeFreezeByteArray marr
+
+unI# :: Int -> Int#
+unI# (I# n#) = n#
+
+-- | Copy a slice of an immutable byte array to a mutable byte array.
+copyByteArray
+  :: PrimMonad m => MutableByteArray (PrimState m)
+                                        -- ^ destination array
+                 -> Int                 -- ^ offset into destination array
+                 -> ByteArray           -- ^ source array
+                 -> Int                 -- ^ offset into source array
+                 -> Int                 -- ^ number of bytes to copy
+                 -> m ()
+{-# INLINE copyByteArray #-}
+copyByteArray (MutableByteArray dst#) doff (ByteArray src#) soff sz
+  = primitive_ (copyByteArray# src# (unI# soff) dst# (unI# doff) (unI# sz))
+
+-- | Copy a slice of a mutable byte array into another array. The two slices
+-- may not overlap.
+copyMutableByteArray
+  :: PrimMonad m => MutableByteArray (PrimState m)
+                                        -- ^ destination array
+                 -> Int                 -- ^ offset into destination array
+                 -> MutableByteArray (PrimState m)
+                                        -- ^ source array
+                 -> Int                 -- ^ offset into source array
+                 -> Int                 -- ^ number of bytes to copy
+                 -> m ()
+{-# INLINE copyMutableByteArray #-}
+copyMutableByteArray (MutableByteArray dst#) doff
+                     (MutableByteArray src#) soff sz
+  = primitive_ (copyMutableByteArray# src# (unI# soff) dst# (unI# doff) (unI# sz))
+
+#if __GLASGOW_HASKELL__ >= 708
+-- | Copy a slice of a byte array to an unmanaged address. These must not
+--   overlap. This function is only available when compiling with GHC 7.8
+--   or newer.
+--
+--   @since 0.6.4.0
+copyByteArrayToAddr
+  :: PrimMonad m
+  => Addr -- ^ destination
+  -> ByteArray -- ^ source array
+  -> Int -- ^ offset into source array
+  -> Int -- ^ number of bytes to copy
+  -> m ()
+{-# INLINE copyByteArrayToAddr #-}
+copyByteArrayToAddr (Addr dst#) (ByteArray src#) soff sz
+  = primitive_ (copyByteArrayToAddr# src# (unI# soff) dst# (unI# sz))
+
+-- | Copy a slice of a mutable byte array to an unmanaged address. These must
+--   not overlap. This function is only available when compiling with GHC 7.8
+--   or newer.
+--
+--   @since 0.6.4.0
+copyMutableByteArrayToAddr
+  :: PrimMonad m
+  => Addr -- ^ destination
+  -> MutableByteArray (PrimState m) -- ^ source array
+  -> Int -- ^ offset into source array
+  -> Int -- ^ number of bytes to copy
+  -> m ()
+{-# INLINE copyMutableByteArrayToAddr #-}
+copyMutableByteArrayToAddr (Addr dst#) (MutableByteArray src#) soff sz
+  = primitive_ (copyMutableByteArrayToAddr# src# (unI# soff) dst# (unI# sz))
+#endif
+
+-- | Copy a slice of a mutable byte array into another, potentially
+-- overlapping array.
+moveByteArray
+  :: PrimMonad m => MutableByteArray (PrimState m)
+                                        -- ^ destination array
+                 -> Int                 -- ^ offset into destination array
+                 -> MutableByteArray (PrimState m)
+                                        -- ^ source array
+                 -> Int                 -- ^ offset into source array
+                 -> Int                 -- ^ number of bytes to copy
+                 -> m ()
+{-# INLINE moveByteArray #-}
+moveByteArray (MutableByteArray dst#) doff
+              (MutableByteArray src#) soff sz
+  = unsafePrimToPrim
+  $ memmove_mba dst# (fromIntegral doff) src# (fromIntegral soff)
+                     (fromIntegral sz)
+
+-- | Fill a slice of a mutable byte array with a value. The offset and length
+-- are given in elements of type @a@ rather than in bytes.
+setByteArray
+  :: (Prim a, PrimMonad m) => MutableByteArray (PrimState m) -- ^ array to fill
+                           -> Int                 -- ^ offset into array
+                           -> Int                 -- ^ number of values to fill
+                           -> a                   -- ^ value to fill with
+                           -> m ()
+{-# INLINE setByteArray #-}
+setByteArray (MutableByteArray dst#) (I# doff#) (I# sz#) x
+  = primitive_ (setByteArray# dst# doff# sz# x)
+
+-- | Fill a slice of a mutable byte array with a byte.
+fillByteArray
+  :: PrimMonad m => MutableByteArray (PrimState m)
+                                        -- ^ array to fill
+                 -> Int                 -- ^ offset into array
+                 -> Int                 -- ^ number of bytes to fill
+                 -> Word8               -- ^ byte to fill with
+                 -> m ()
+{-# INLINE fillByteArray #-}
+fillByteArray = setByteArray
+
+foreign import ccall unsafe "primitive-memops.h hsprimitive_memmove"
+  memmove_mba :: MutableByteArray# s -> CInt
+              -> MutableByteArray# s -> CInt
+              -> CSize -> IO ()
+
+instance Data ByteArray where
+  toConstr _ = error "toConstr"
+  gunfold _ _ = error "gunfold"
+  dataTypeOf _ = mkNoRepType "Data.Primitive.ByteArray.ByteArray"
+
+instance Typeable s => Data (MutableByteArray s) where
+  toConstr _ = error "toConstr"
+  gunfold _ _ = error "gunfold"
+  dataTypeOf _ = mkNoRepType "Data.Primitive.ByteArray.MutableByteArray"
+
+-- | @since 0.6.3.0
+instance Show ByteArray where
+  showsPrec _ ba =
+      showString "[" . go 0
+    where
+      go i
+        | i < sizeofByteArray ba = comma . showString "0x" . showHex (indexByteArray ba i :: Word8) . go (i+1)
+        | otherwise              = showChar ']'
+        where
+          comma | i == 0    = id
+                | otherwise = showString ", "
+
+
+compareByteArrays :: ByteArray -> ByteArray -> Int -> Ordering
+{-# INLINE compareByteArrays #-}
+#if __GLASGOW_HASKELL__ >= 804
+compareByteArrays (ByteArray ba1#) (ByteArray ba2#) (I# n#) =
+  compare (I# (compareByteArrays# ba1# 0# ba2# 0# n#)) 0
+#else
+-- Emulate GHC 8.4's 'GHC.Prim.compareByteArrays#'
+compareByteArrays (ByteArray ba1#) (ByteArray ba2#) (I# n#)
+    = compare (fromCInt (unsafeDupablePerformIO (memcmp_ba ba1# ba2# n))) 0
+  where
+    n = fromIntegral (I# n#) :: CSize
+    fromCInt = fromIntegral :: CInt -> Int
+
+foreign import ccall unsafe "primitive-memops.h hsprimitive_memcmp"
+  memcmp_ba :: ByteArray# -> ByteArray# -> CSize -> IO CInt
+#endif
+
+
+sameByteArray :: ByteArray# -> ByteArray# -> Bool
+sameByteArray ba1 ba2 =
+    case reallyUnsafePtrEquality# (unsafeCoerce# ba1 :: ()) (unsafeCoerce# ba2 :: ()) of
+#if __GLASGOW_HASKELL__ >= 708
+      r -> isTrue# r
+#else
+      1# -> True
+      0# -> False
+#endif
+
+-- | @since 0.6.3.0
+instance Eq ByteArray where
+  ba1@(ByteArray ba1#) == ba2@(ByteArray ba2#)
+    | sameByteArray ba1# ba2# = True
+    | n1 /= n2 = False
+    | otherwise = compareByteArrays ba1 ba2 n1 == EQ
+    where
+      n1 = sizeofByteArray ba1
+      n2 = sizeofByteArray ba2
+
+-- | Non-lexicographic ordering. This compares the lengths of
+-- the byte arrays first and uses a lexicographic ordering if
+-- the lengths are equal. Subject to change between major versions.
+-- 
+-- @since 0.6.3.0
+instance Ord ByteArray where
+  ba1@(ByteArray ba1#) `compare` ba2@(ByteArray ba2#)
+    | sameByteArray ba1# ba2# = EQ
+    | n1 /= n2 = n1 `compare` n2
+    | otherwise = compareByteArrays ba1 ba2 n1
+    where
+      n1 = sizeofByteArray ba1
+      n2 = sizeofByteArray ba2
+-- Note: On GHC 8.4, the primop compareByteArrays# performs a check for pointer
+-- equality as a shortcut, so the check here is actually redundant. However, it
+-- is included here because it is likely better to check for pointer equality
+-- before checking for length equality. Getting the length requires deferencing
+-- the pointers, which could cause accesses to memory that is not in the cache.
+-- By contrast, a pointer equality check is always extremely cheap.
+
+appendByteArray :: ByteArray -> ByteArray -> ByteArray
+appendByteArray a b = runST $ do
+  marr <- newByteArray (sizeofByteArray a + sizeofByteArray b)
+  copyByteArray marr 0 a 0 (sizeofByteArray a)
+  copyByteArray marr (sizeofByteArray a) b 0 (sizeofByteArray b)
+  unsafeFreezeByteArray marr
+
+concatByteArray :: [ByteArray] -> ByteArray
+concatByteArray arrs = runST $ do
+  let len = calcLength arrs 0
+  marr <- newByteArray len
+  pasteByteArrays marr 0 arrs
+  unsafeFreezeByteArray marr
+
+pasteByteArrays :: MutableByteArray s -> Int -> [ByteArray] -> ST s ()
+pasteByteArrays !_ !_ [] = return ()
+pasteByteArrays !marr !ix (x : xs) = do
+  copyByteArray marr ix x 0 (sizeofByteArray x)
+  pasteByteArrays marr (ix + sizeofByteArray x) xs
+
+calcLength :: [ByteArray] -> Int -> Int
+calcLength [] !n = n
+calcLength (x : xs) !n = calcLength xs (sizeofByteArray x + n)
+
+emptyByteArray :: ByteArray
+emptyByteArray = runST (newByteArray 0 >>= unsafeFreezeByteArray)
+
+replicateByteArray :: Int -> ByteArray -> ByteArray
+replicateByteArray n arr = runST $ do
+  marr <- newByteArray (n * sizeofByteArray arr)
+  let go i = if i < n
+        then do
+          copyByteArray marr (i * sizeofByteArray arr) arr 0 (sizeofByteArray arr)
+          go (i + 1)
+        else return ()
+  go 0
+  unsafeFreezeByteArray marr
+
+#if MIN_VERSION_base(4,9,0)
+instance SG.Semigroup ByteArray where
+  (<>) = appendByteArray
+  sconcat = mconcat . F.toList
+  stimes i arr
+    | itgr < 1 = emptyByteArray
+    | itgr <= (fromIntegral (maxBound :: Int)) = replicateByteArray (fromIntegral itgr) arr
+    | otherwise = error "Data.Primitive.ByteArray#stimes: cannot allocate the requested amount of memory"
+    where itgr = toInteger i :: Integer
+#endif
+
+instance Monoid ByteArray where
+  mempty = emptyByteArray
+#if !(MIN_VERSION_base(4,11,0))
+  mappend = appendByteArray
+#endif
+  mconcat = concatByteArray
+
+#if __GLASGOW_HASKELL__ >= 708
+-- | @since 0.6.3.0
+instance Exts.IsList ByteArray where
+  type Item ByteArray = Word8
+
+  toList = foldrByteArray (:) []
+  fromList xs = byteArrayFromListN (length xs) xs
+  fromListN = byteArrayFromListN
+#endif
+
+die :: String -> String -> a
+die fun problem = error $ "Data.Primitive.ByteArray." ++ fun ++ ": " ++ problem
+

third_party/bazel/rules_haskell/examples/primitive/Data/Primitive/Internal/Compat.hs

@@ -0,0 +1,38 @@
+{-# LANGUAGE CPP, MagicHash #-}
+
+-- |
+-- Module      : Data.Primitive.Internal.Compat
+-- Copyright   : (c) Roman Leshchinskiy 2011-2012
+-- License     : BSD-style
+--
+-- Maintainer  : Roman Leshchinskiy <rl@cse.unsw.edu.au>
+-- Portability : non-portable
+--
+-- Compatibility functions
+--
+
+module Data.Primitive.Internal.Compat (
+    isTrue#
+  , mkNoRepType
+  ) where
+
+#if MIN_VERSION_base(4,2,0)
+import Data.Data (mkNoRepType)
+#else
+import Data.Data (mkNorepType)
+#endif
+
+#if MIN_VERSION_base(4,7,0)
+import GHC.Exts (isTrue#)
+#endif
+
+
+
+#if !MIN_VERSION_base(4,2,0)
+mkNoRepType = mkNorepType
+#endif
+
+#if !MIN_VERSION_base(4,7,0)
+isTrue# :: Bool -> Bool
+isTrue# b = b
+#endif

third_party/bazel/rules_haskell/examples/primitive/Data/Primitive/Internal/Operations.hs

@@ -0,0 +1,90 @@
+{-# LANGUAGE MagicHash, UnliftedFFITypes #-}
+
+-- |
+-- Module      : Data.Primitive.Internal.Operations
+-- Copyright   : (c) Roman Leshchinskiy 2011-2012
+-- License     : BSD-style
+--
+-- Maintainer  : Roman Leshchinskiy <rl@cse.unsw.edu.au>
+-- Portability : non-portable
+--
+-- Internal operations
+--
+
+
+module Data.Primitive.Internal.Operations (
+  setWord8Array#, setWord16Array#, setWord32Array#,
+  setWord64Array#, setWordArray#,
+  setInt8Array#, setInt16Array#, setInt32Array#,
+  setInt64Array#, setIntArray#,
+  setAddrArray#, setFloatArray#, setDoubleArray#, setWideCharArray#,
+
+  setWord8OffAddr#, setWord16OffAddr#, setWord32OffAddr#,
+  setWord64OffAddr#, setWordOffAddr#,
+  setInt8OffAddr#, setInt16OffAddr#, setInt32OffAddr#,
+  setInt64OffAddr#, setIntOffAddr#,
+  setAddrOffAddr#, setFloatOffAddr#, setDoubleOffAddr#, setWideCharOffAddr#
+) where
+
+import Data.Primitive.MachDeps (Word64_#, Int64_#)
+import Foreign.C.Types
+import GHC.Prim
+
+foreign import ccall unsafe "primitive-memops.h hsprimitive_memset_Word8"
+  setWord8Array# :: MutableByteArray# s -> CPtrdiff -> CSize -> Word# -> IO ()
+foreign import ccall unsafe "primitive-memops.h hsprimitive_memset_Word16"
+  setWord16Array# :: MutableByteArray# s -> CPtrdiff -> CSize -> Word# -> IO ()
+foreign import ccall unsafe "primitive-memops.h hsprimitive_memset_Word32"
+  setWord32Array# :: MutableByteArray# s -> CPtrdiff -> CSize -> Word# -> IO ()
+foreign import ccall unsafe "primitive-memops.h hsprimitive_memset_Word64"
+  setWord64Array# :: MutableByteArray# s -> CPtrdiff -> CSize -> Word64_# -> IO ()
+foreign import ccall unsafe "primitive-memops.h hsprimitive_memset_Word"
+  setWordArray# :: MutableByteArray# s -> CPtrdiff -> CSize -> Word# -> IO ()
+foreign import ccall unsafe "primitive-memops.h hsprimitive_memset_Word8"
+  setInt8Array# :: MutableByteArray# s -> CPtrdiff -> CSize -> Int# -> IO ()
+foreign import ccall unsafe "primitive-memops.h hsprimitive_memset_Word16"
+  setInt16Array# :: MutableByteArray# s -> CPtrdiff -> CSize -> Int# -> IO ()
+foreign import ccall unsafe "primitive-memops.h hsprimitive_memset_Word32"
+  setInt32Array# :: MutableByteArray# s -> CPtrdiff -> CSize -> Int# -> IO ()
+foreign import ccall unsafe "primitive-memops.h hsprimitive_memset_Word64"
+  setInt64Array# :: MutableByteArray# s -> CPtrdiff -> CSize -> Int64_# -> IO ()
+foreign import ccall unsafe "primitive-memops.h hsprimitive_memset_Word"
+  setIntArray# :: MutableByteArray# s -> CPtrdiff -> CSize -> Int# -> IO ()
+foreign import ccall unsafe "primitive-memops.h hsprimitive_memset_Ptr"
+  setAddrArray# :: MutableByteArray# s -> CPtrdiff -> CSize -> Addr# -> IO ()
+foreign import ccall unsafe "primitive-memops.h hsprimitive_memset_Float"
+  setFloatArray# :: MutableByteArray# s -> CPtrdiff -> CSize -> Float# -> IO ()
+foreign import ccall unsafe "primitive-memops.h hsprimitive_memset_Double"
+  setDoubleArray# :: MutableByteArray# s -> CPtrdiff -> CSize -> Double# -> IO ()
+foreign import ccall unsafe "primitive-memops.h hsprimitive_memset_Char"
+  setWideCharArray# :: MutableByteArray# s -> CPtrdiff -> CSize -> Char# -> IO ()
+
+foreign import ccall unsafe "primitive-memops.h hsprimitive_memset_Word8"
+  setWord8OffAddr# :: Addr# -> CPtrdiff -> CSize -> Word# -> IO ()
+foreign import ccall unsafe "primitive-memops.h hsprimitive_memset_Word16"
+  setWord16OffAddr# :: Addr# -> CPtrdiff -> CSize -> Word# -> IO ()
+foreign import ccall unsafe "primitive-memops.h hsprimitive_memset_Word32"
+  setWord32OffAddr# :: Addr# -> CPtrdiff -> CSize -> Word# -> IO ()
+foreign import ccall unsafe "primitive-memops.h hsprimitive_memset_Word64"
+  setWord64OffAddr# :: Addr# -> CPtrdiff -> CSize -> Word64_# -> IO ()
+foreign import ccall unsafe "primitive-memops.h hsprimitive_memset_Word"
+  setWordOffAddr# :: Addr# -> CPtrdiff -> CSize -> Word# -> IO ()
+foreign import ccall unsafe "primitive-memops.h hsprimitive_memset_Word8"
+  setInt8OffAddr# :: Addr# -> CPtrdiff -> CSize -> Int# -> IO ()
+foreign import ccall unsafe "primitive-memops.h hsprimitive_memset_Word16"
+  setInt16OffAddr# :: Addr# -> CPtrdiff -> CSize -> Int# -> IO ()
+foreign import ccall unsafe "primitive-memops.h hsprimitive_memset_Word32"
+  setInt32OffAddr# :: Addr# -> CPtrdiff -> CSize -> Int# -> IO ()
+foreign import ccall unsafe "primitive-memops.h hsprimitive_memset_Word64"
+  setInt64OffAddr# :: Addr# -> CPtrdiff -> CSize -> Int64_# -> IO ()
+foreign import ccall unsafe "primitive-memops.h hsprimitive_memset_Word"
+  setIntOffAddr# :: Addr# -> CPtrdiff -> CSize -> Int# -> IO ()
+foreign import ccall unsafe "primitive-memops.h hsprimitive_memset_Ptr"
+  setAddrOffAddr# :: Addr# -> CPtrdiff -> CSize -> Addr# -> IO ()
+foreign import ccall unsafe "primitive-memops.h hsprimitive_memset_Float"
+  setFloatOffAddr# :: Addr# -> CPtrdiff -> CSize -> Float# -> IO ()
+foreign import ccall unsafe "primitive-memops.h hsprimitive_memset_Double"
+  setDoubleOffAddr# :: Addr# -> CPtrdiff -> CSize -> Double# -> IO ()
+foreign import ccall unsafe "primitive-memops.h hsprimitive_memset_Char"
+  setWideCharOffAddr# :: Addr# -> CPtrdiff -> CSize -> Char# -> IO ()
+

third_party/bazel/rules_haskell/examples/primitive/Data/Primitive/MVar.hs

@@ -0,0 +1,155 @@
+{-# LANGUAGE BangPatterns #-}
+{-# LANGUAGE CPP #-}
+{-# LANGUAGE MagicHash #-}
+{-# LANGUAGE UnboxedTuples #-}
+
+-- |
+-- Module      : Data.Primitive.MVar
+-- License     : BSD2
+-- Portability : non-portable
+--
+-- Primitive operations on @MVar@. This module provides a similar interface
+-- to "Control.Concurrent.MVar". However, the functions are generalized to
+-- work in any 'PrimMonad' instead of only working in 'IO'. Note that all
+-- of the functions here are completely deterministic. Users of 'MVar' are
+-- responsible for designing abstractions that guarantee determinism in
+-- the presence of multi-threading.
+--
+-- @since 0.6.4.0
+module Data.Primitive.MVar
+  ( MVar(..)
+  , newMVar
+  , isEmptyMVar
+  , newEmptyMVar
+  , putMVar
+  , readMVar
+  , takeMVar
+  , tryPutMVar
+  , tryReadMVar
+  , tryTakeMVar
+  ) where
+
+import Control.Monad.Primitive
+import Data.Primitive.Internal.Compat (isTrue#)
+import GHC.Exts (MVar#,newMVar#,takeMVar#,sameMVar#,putMVar#,tryTakeMVar#,
+  isEmptyMVar#,tryPutMVar#,(/=#))
+
+#if __GLASGOW_HASKELL__ >= 708
+import GHC.Exts (readMVar#,tryReadMVar#)
+#endif
+
+data MVar s a = MVar (MVar# s a)
+
+instance Eq (MVar s a) where
+  MVar mvar1# == MVar mvar2# = isTrue# (sameMVar# mvar1# mvar2#)
+
+-- | Create a new 'MVar' that is initially empty.
+newEmptyMVar :: PrimMonad m => m (MVar (PrimState m) a)
+newEmptyMVar = primitive $ \ s# ->
+  case newMVar# s# of
+    (# s2#, svar# #) -> (# s2#, MVar svar# #)
+
+
+-- | Create a new 'MVar' that holds the supplied argument.
+newMVar :: PrimMonad m => a -> m (MVar (PrimState m) a)
+newMVar value =
+  newEmptyMVar >>= \ mvar ->
+  putMVar mvar value >>
+  return mvar
+
+-- | Return the contents of the 'MVar'.  If the 'MVar' is currently
+-- empty, 'takeMVar' will wait until it is full.  After a 'takeMVar',
+-- the 'MVar' is left empty.
+takeMVar :: PrimMonad m => MVar (PrimState m) a -> m a
+takeMVar (MVar mvar#) = primitive $ \ s# -> takeMVar# mvar# s#
+
+-- | Atomically read the contents of an 'MVar'.  If the 'MVar' is
+-- currently empty, 'readMVar' will wait until it is full.
+-- 'readMVar' is guaranteed to receive the next 'putMVar'.
+--
+-- /Multiple Wakeup:/ 'readMVar' is multiple-wakeup, so when multiple readers
+-- are blocked on an 'MVar', all of them are woken up at the same time.
+--
+-- /Compatibility note:/ On GHCs prior to 7.8, 'readMVar' is a combination
+-- of 'takeMVar' and 'putMVar'. Consequently, its behavior differs in the
+-- following ways:
+--
+-- * It is single-wakeup instead of multiple-wakeup.
+-- * It might not receive the value from the next call to 'putMVar' if
+--   there is already a pending thread blocked on 'takeMVar'.
+-- * If another thread puts a value in the 'MVar' in between the
+--   calls to 'takeMVar' and 'putMVar', that value may be overridden.
+readMVar :: PrimMonad m => MVar (PrimState m) a -> m a
+#if __GLASGOW_HASKELL__ >= 708
+readMVar (MVar mvar#) = primitive $ \ s# -> readMVar# mvar# s#
+#else
+readMVar mv = do
+  a <- takeMVar mv
+  putMVar mv a
+  return a
+#endif
+
+-- |Put a value into an 'MVar'.  If the 'MVar' is currently full,
+-- 'putMVar' will wait until it becomes empty.
+putMVar :: PrimMonad m => MVar (PrimState m) a -> a -> m ()
+putMVar (MVar mvar#) x = primitive_ (putMVar# mvar# x)
+
+-- |A non-blocking version of 'takeMVar'.  The 'tryTakeMVar' function
+-- returns immediately, with 'Nothing' if the 'MVar' was empty, or
+-- @'Just' a@ if the 'MVar' was full with contents @a@.  After 'tryTakeMVar',
+-- the 'MVar' is left empty.
+tryTakeMVar :: PrimMonad m => MVar (PrimState m) a -> m (Maybe a)
+tryTakeMVar (MVar m) = primitive $ \ s ->
+  case tryTakeMVar# m s of
+    (# s', 0#, _ #) -> (# s', Nothing #) -- MVar is empty
+    (# s', _,  a #) -> (# s', Just a  #) -- MVar is full
+
+
+-- |A non-blocking version of 'putMVar'.  The 'tryPutMVar' function
+-- attempts to put the value @a@ into the 'MVar', returning 'True' if
+-- it was successful, or 'False' otherwise.
+tryPutMVar :: PrimMonad m => MVar (PrimState m) a -> a -> m Bool
+tryPutMVar (MVar mvar#) x = primitive $ \ s# ->
+    case tryPutMVar# mvar# x s# of
+        (# s, 0# #) -> (# s, False #)
+        (# s, _  #) -> (# s, True #)
+
+-- | A non-blocking version of 'readMVar'.  The 'tryReadMVar' function
+-- returns immediately, with 'Nothing' if the 'MVar' was empty, or
+-- @'Just' a@ if the 'MVar' was full with contents @a@.
+--
+-- /Compatibility note:/ On GHCs prior to 7.8, 'tryReadMVar' is a combination
+-- of 'tryTakeMVar' and 'putMVar'. Consequently, its behavior differs in the
+-- following ways:
+--
+-- * It is single-wakeup instead of multiple-wakeup.
+-- * In the presence of other threads calling 'putMVar', 'tryReadMVar'
+--   may block.
+-- * If another thread puts a value in the 'MVar' in between the
+--   calls to 'tryTakeMVar' and 'putMVar', that value may be overridden.
+tryReadMVar :: PrimMonad m => MVar (PrimState m) a -> m (Maybe a)
+#if __GLASGOW_HASKELL__ >= 708
+tryReadMVar (MVar m) = primitive $ \ s ->
+    case tryReadMVar# m s of
+        (# s', 0#, _ #) -> (# s', Nothing #)      -- MVar is empty
+        (# s', _,  a #) -> (# s', Just a  #)      -- MVar is full
+#else
+tryReadMVar mv = do
+  ma <- tryTakeMVar mv
+  case ma of
+    Just a -> do
+      putMVar mv a
+      return (Just a)
+    Nothing -> return Nothing
+#endif
+
+-- | Check whether a given 'MVar' is empty.
+--
+-- Notice that the boolean value returned  is just a snapshot of
+-- the state of the MVar. By the time you get to react on its result,
+-- the MVar may have been filled (or emptied) - so be extremely
+-- careful when using this operation.   Use 'tryTakeMVar' instead if possible.
+isEmptyMVar :: PrimMonad m => MVar (PrimState m) a -> m Bool
+isEmptyMVar (MVar mv#) = primitive $ \ s# ->
+  case isEmptyMVar# mv# s# of
+    (# s2#, flg #) -> (# s2#, isTrue# (flg /=# 0#) #)

third_party/bazel/rules_haskell/examples/primitive/Data/Primitive/MachDeps.hs

@@ -0,0 +1,123 @@
+{-# LANGUAGE CPP, MagicHash #-}
+-- |
+-- Module      : Data.Primitive.MachDeps
+-- Copyright   : (c) Roman Leshchinskiy 2009-2012
+-- License     : BSD-style
+--
+-- Maintainer  : Roman Leshchinskiy <rl@cse.unsw.edu.au>
+-- Portability : non-portable
+--
+-- Machine-dependent constants
+--
+
+module Data.Primitive.MachDeps where
+
+#include "MachDeps.h"
+
+import GHC.Prim
+
+sIZEOF_CHAR,
+ aLIGNMENT_CHAR,
+
+ sIZEOF_INT,
+ aLIGNMENT_INT,
+
+ sIZEOF_WORD,
+ aLIGNMENT_WORD,
+
+ sIZEOF_DOUBLE,
+ aLIGNMENT_DOUBLE,
+
+ sIZEOF_FLOAT,
+ aLIGNMENT_FLOAT,
+
+ sIZEOF_PTR,
+ aLIGNMENT_PTR,
+
+ sIZEOF_FUNPTR,
+ aLIGNMENT_FUNPTR,
+
+ sIZEOF_STABLEPTR,
+ aLIGNMENT_STABLEPTR,
+
+ sIZEOF_INT8,
+ aLIGNMENT_INT8,
+
+ sIZEOF_WORD8,
+ aLIGNMENT_WORD8,
+
+ sIZEOF_INT16,
+ aLIGNMENT_INT16,
+
+ sIZEOF_WORD16,
+ aLIGNMENT_WORD16,
+
+ sIZEOF_INT32,
+ aLIGNMENT_INT32,
+
+ sIZEOF_WORD32,
+ aLIGNMENT_WORD32,
+
+ sIZEOF_INT64,
+ aLIGNMENT_INT64,
+
+ sIZEOF_WORD64,
+ aLIGNMENT_WORD64 :: Int
+
+
+sIZEOF_CHAR = SIZEOF_HSCHAR
+aLIGNMENT_CHAR = ALIGNMENT_HSCHAR
+
+sIZEOF_INT = SIZEOF_HSINT
+aLIGNMENT_INT = ALIGNMENT_HSINT
+
+sIZEOF_WORD = SIZEOF_HSWORD
+aLIGNMENT_WORD = ALIGNMENT_HSWORD
+
+sIZEOF_DOUBLE = SIZEOF_HSDOUBLE
+aLIGNMENT_DOUBLE = ALIGNMENT_HSDOUBLE
+
+sIZEOF_FLOAT = SIZEOF_HSFLOAT
+aLIGNMENT_FLOAT = ALIGNMENT_HSFLOAT
+
+sIZEOF_PTR = SIZEOF_HSPTR
+aLIGNMENT_PTR = ALIGNMENT_HSPTR
+
+sIZEOF_FUNPTR = SIZEOF_HSFUNPTR
+aLIGNMENT_FUNPTR = ALIGNMENT_HSFUNPTR
+
+sIZEOF_STABLEPTR = SIZEOF_HSSTABLEPTR
+aLIGNMENT_STABLEPTR = ALIGNMENT_HSSTABLEPTR
+
+sIZEOF_INT8 = SIZEOF_INT8
+aLIGNMENT_INT8 = ALIGNMENT_INT8
+
+sIZEOF_WORD8 = SIZEOF_WORD8
+aLIGNMENT_WORD8 = ALIGNMENT_WORD8
+
+sIZEOF_INT16 = SIZEOF_INT16
+aLIGNMENT_INT16 = ALIGNMENT_INT16
+
+sIZEOF_WORD16 = SIZEOF_WORD16
+aLIGNMENT_WORD16 = ALIGNMENT_WORD16
+
+sIZEOF_INT32 = SIZEOF_INT32
+aLIGNMENT_INT32 = ALIGNMENT_INT32
+
+sIZEOF_WORD32 = SIZEOF_WORD32
+aLIGNMENT_WORD32 = ALIGNMENT_WORD32
+
+sIZEOF_INT64 = SIZEOF_INT64
+aLIGNMENT_INT64 = ALIGNMENT_INT64
+
+sIZEOF_WORD64 = SIZEOF_WORD64
+aLIGNMENT_WORD64 = ALIGNMENT_WORD64
+
+#if WORD_SIZE_IN_BITS == 32
+type Word64_# = Word64#
+type Int64_# = Int64#
+#else
+type Word64_# = Word#
+type Int64_# = Int#
+#endif
+

third_party/bazel/rules_haskell/examples/primitive/Data/Primitive/MutVar.hs

@@ -0,0 +1,86 @@
+{-# LANGUAGE MagicHash, UnboxedTuples, DeriveDataTypeable #-}
+
+-- |
+-- Module      : Data.Primitive.MutVar
+-- Copyright   : (c) Justin Bonnar 2011, Roman Leshchinskiy 2011-2012
+-- License     : BSD-style
+--
+-- Maintainer  : Roman Leshchinskiy <rl@cse.unsw.edu.au>
+-- Portability : non-portable
+--
+-- Primitive boxed mutable variables
+--
+
+module Data.Primitive.MutVar (
+  MutVar(..),
+
+  newMutVar,
+  readMutVar,
+  writeMutVar,
+
+  atomicModifyMutVar,
+  atomicModifyMutVar',
+  modifyMutVar,
+  modifyMutVar'
+) where
+
+import Control.Monad.Primitive ( PrimMonad(..), primitive_ )
+import GHC.Prim ( MutVar#, sameMutVar#, newMutVar#,
+                  readMutVar#, writeMutVar#, atomicModifyMutVar# )
+import Data.Primitive.Internal.Compat ( isTrue# )
+import Data.Typeable ( Typeable )
+
+-- | A 'MutVar' behaves like a single-element mutable array associated
+-- with a primitive state token.
+data MutVar s a = MutVar (MutVar# s a)
+  deriving ( Typeable )
+
+instance Eq (MutVar s a) where
+  MutVar mva# == MutVar mvb# = isTrue# (sameMutVar# mva# mvb#)
+
+-- | Create a new 'MutVar' with the specified initial value
+newMutVar :: PrimMonad m => a -> m (MutVar (PrimState m) a)
+{-# INLINE newMutVar #-}
+newMutVar initialValue = primitive $ \s# ->
+  case newMutVar# initialValue s# of
+    (# s'#, mv# #) -> (# s'#, MutVar mv# #)
+
+-- | Read the value of a 'MutVar'
+readMutVar :: PrimMonad m => MutVar (PrimState m) a -> m a
+{-# INLINE readMutVar #-}
+readMutVar (MutVar mv#) = primitive (readMutVar# mv#)
+
+-- | Write a new value into a 'MutVar'
+writeMutVar :: PrimMonad m => MutVar (PrimState m) a -> a -> m ()
+{-# INLINE writeMutVar #-}
+writeMutVar (MutVar mv#) newValue = primitive_ (writeMutVar# mv# newValue)
+
+-- | Atomically mutate the contents of a 'MutVar'
+atomicModifyMutVar :: PrimMonad m => MutVar (PrimState m) a -> (a -> (a,b)) -> m b
+{-# INLINE atomicModifyMutVar #-}
+atomicModifyMutVar (MutVar mv#) f = primitive $ atomicModifyMutVar# mv# f
+
+-- | Strict version of 'atomicModifyMutVar'. This forces both the value stored
+-- in the 'MutVar' as well as the value returned.
+atomicModifyMutVar' :: PrimMonad m => MutVar (PrimState m) a -> (a -> (a, b)) -> m b
+{-# INLINE atomicModifyMutVar' #-}
+atomicModifyMutVar' mv f = do
+  b <- atomicModifyMutVar mv force
+  b `seq` return b
+  where
+    force x = let (a, b) = f x in (a, a `seq` b)
+
+-- | Mutate the contents of a 'MutVar'
+modifyMutVar :: PrimMonad m => MutVar (PrimState m) a -> (a -> a) -> m ()
+{-# INLINE modifyMutVar #-}
+modifyMutVar (MutVar mv#) g = primitive_ $ \s# ->
+  case readMutVar# mv# s# of
+    (# s'#, a #) -> writeMutVar# mv# (g a) s'#
+
+-- | Strict version of 'modifyMutVar'
+modifyMutVar' :: PrimMonad m => MutVar (PrimState m) a -> (a -> a) -> m ()
+{-# INLINE modifyMutVar' #-}
+modifyMutVar' (MutVar mv#) g = primitive_ $ \s# ->
+  case readMutVar# mv# s# of
+    (# s'#, a #) -> let a' = g a in a' `seq` writeMutVar# mv# a' s'#
+

third_party/bazel/rules_haskell/examples/primitive/Data/Primitive/PrimArray.hs

@@ -0,0 +1,969 @@
+{-# LANGUAGE BangPatterns #-}
+{-# LANGUAGE CPP #-}
+{-# LANGUAGE MagicHash #-}
+{-# LANGUAGE RankNTypes #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE UnboxedTuples #-}
+
+{-# OPTIONS_GHC -Wall #-}
+
+-- |
+-- Module      : Data.Primitive.PrimArray
+-- Copyright   : (c) Roman Leshchinskiy 2009-2012
+-- License     : BSD-style
+--
+-- Maintainer  : Roman Leshchinskiy <rl@cse.unsw.edu.au>
+-- Portability : non-portable
+--
+-- Arrays of unboxed primitive types. The function provided by this module
+-- match the behavior of those provided by @Data.Primitive.ByteArray@, and
+-- the underlying types and primops that back them are the same.
+-- However, the type constructors 'PrimArray' and 'MutablePrimArray' take one additional
+-- argument than their respective counterparts 'ByteArray' and 'MutableByteArray'.
+-- This argument is used to designate the type of element in the array.
+-- Consequently, all function this modules accepts length and incides in
+-- terms of elements, not bytes.
+--
+-- @since 0.6.4.0
+module Data.Primitive.PrimArray
+  ( -- * Types
+    PrimArray(..)
+  , MutablePrimArray(..)
+    -- * Allocation
+  , newPrimArray
+  , resizeMutablePrimArray
+#if __GLASGOW_HASKELL__ >= 710
+  , shrinkMutablePrimArray
+#endif
+    -- * Element Access
+  , readPrimArray
+  , writePrimArray
+  , indexPrimArray
+    -- * Freezing and Thawing
+  , unsafeFreezePrimArray
+  , unsafeThawPrimArray
+    -- * Block Operations
+  , copyPrimArray
+  , copyMutablePrimArray
+#if __GLASGOW_HASKELL__ >= 708
+  , copyPrimArrayToPtr
+  , copyMutablePrimArrayToPtr
+#endif
+  , setPrimArray
+    -- * Information
+  , sameMutablePrimArray
+  , getSizeofMutablePrimArray
+  , sizeofMutablePrimArray
+  , sizeofPrimArray
+    -- * List Conversion
+  , primArrayToList
+  , primArrayFromList
+  , primArrayFromListN
+    -- * Folding
+  , foldrPrimArray
+  , foldrPrimArray'
+  , foldlPrimArray
+  , foldlPrimArray'
+  , foldlPrimArrayM'
+    -- * Effectful Folding
+  , traversePrimArray_
+  , itraversePrimArray_
+    -- * Map/Create
+  , mapPrimArray
+  , imapPrimArray
+  , generatePrimArray
+  , replicatePrimArray
+  , filterPrimArray
+  , mapMaybePrimArray
+    -- * Effectful Map/Create
+    -- $effectfulMapCreate
+    -- ** Lazy Applicative
+  , traversePrimArray
+  , itraversePrimArray
+  , generatePrimArrayA
+  , replicatePrimArrayA
+  , filterPrimArrayA
+  , mapMaybePrimArrayA
+    -- ** Strict Primitive Monadic
+  , traversePrimArrayP
+  , itraversePrimArrayP
+  , generatePrimArrayP
+  , replicatePrimArrayP
+  , filterPrimArrayP
+  , mapMaybePrimArrayP
+  ) where
+
+import GHC.Prim
+import GHC.Base ( Int(..) )
+import GHC.Exts (build)
+import GHC.Ptr
+import Data.Primitive.Internal.Compat (isTrue#)
+import Data.Primitive.Types
+import Data.Primitive.ByteArray (ByteArray(..))
+import Data.Monoid (Monoid(..),(<>))
+import Control.Applicative
+import Control.Monad.Primitive
+import Control.Monad.ST
+import qualified Data.List as L
+import qualified Data.Primitive.ByteArray as PB
+import qualified Data.Primitive.Types as PT
+
+#if MIN_VERSION_base(4,7,0)
+import GHC.Exts (IsList(..))
+#endif
+
+#if MIN_VERSION_base(4,9,0)
+import Data.Semigroup (Semigroup)
+import qualified Data.Semigroup as SG
+#endif
+
+-- | Arrays of unboxed elements. This accepts types like 'Double', 'Char',
+-- 'Int', and 'Word', as well as their fixed-length variants ('Word8',
+-- 'Word16', etc.). Since the elements are unboxed, a 'PrimArray' is strict
+-- in its elements. This differs from the behavior of 'Array', which is lazy
+-- in its elements.
+data PrimArray a = PrimArray ByteArray#
+
+-- | Mutable primitive arrays associated with a primitive state token.
+-- These can be written to and read from in a monadic context that supports
+-- sequencing such as 'IO' or 'ST'. Typically, a mutable primitive array will
+-- be built and then convert to an immutable primitive array using
+-- 'unsafeFreezePrimArray'. However, it is also acceptable to simply discard
+-- a mutable primitive array since it lives in managed memory and will be
+-- garbage collected when no longer referenced.
+data MutablePrimArray s a = MutablePrimArray (MutableByteArray# s)
+
+sameByteArray :: ByteArray# -> ByteArray# -> Bool
+sameByteArray ba1 ba2 =
+    case reallyUnsafePtrEquality# (unsafeCoerce# ba1 :: ()) (unsafeCoerce# ba2 :: ()) of
+#if __GLASGOW_HASKELL__ >= 708
+      r -> isTrue# r
+#else
+      1# -> True
+      _ -> False
+#endif
+
+-- | @since 0.6.4.0
+instance (Eq a, Prim a) => Eq (PrimArray a) where
+  a1@(PrimArray ba1#) == a2@(PrimArray ba2#)
+    | sameByteArray ba1# ba2# = True
+    | sz1 /= sz2 = False
+    | otherwise = loop (quot sz1 (sizeOf (undefined :: a)) - 1)
+    where
+    -- Here, we take the size in bytes, not in elements. We do this
+    -- since it allows us to defer performing the division to
+    -- calculate the size in elements.
+    sz1 = PB.sizeofByteArray (ByteArray ba1#)
+    sz2 = PB.sizeofByteArray (ByteArray ba2#)
+    loop !i
+      | i < 0 = True
+      | otherwise = indexPrimArray a1 i == indexPrimArray a2 i && loop (i-1)
+
+-- | Lexicographic ordering. Subject to change between major versions.
+-- 
+--   @since 0.6.4.0
+instance (Ord a, Prim a) => Ord (PrimArray a) where
+  compare a1@(PrimArray ba1#) a2@(PrimArray ba2#)
+    | sameByteArray ba1# ba2# = EQ
+    | otherwise = loop 0
+    where
+    sz1 = PB.sizeofByteArray (ByteArray ba1#)
+    sz2 = PB.sizeofByteArray (ByteArray ba2#)
+    sz = quot (min sz1 sz2) (sizeOf (undefined :: a))
+    loop !i
+      | i < sz = compare (indexPrimArray a1 i) (indexPrimArray a2 i) <> loop (i+1)
+      | otherwise = compare sz1 sz2
+
+#if MIN_VERSION_base(4,7,0)
+-- | @since 0.6.4.0
+instance Prim a => IsList (PrimArray a) where
+  type Item (PrimArray a) = a
+  fromList = primArrayFromList
+  fromListN = primArrayFromListN
+  toList = primArrayToList
+#endif
+
+-- | @since 0.6.4.0
+instance (Show a, Prim a) => Show (PrimArray a) where
+  showsPrec p a = showParen (p > 10) $
+    showString "fromListN " . shows (sizeofPrimArray a) . showString " "
+      . shows (primArrayToList a)
+
+die :: String -> String -> a
+die fun problem = error $ "Data.Primitive.PrimArray." ++ fun ++ ": " ++ problem
+
+primArrayFromList :: Prim a => [a] -> PrimArray a
+primArrayFromList vs = primArrayFromListN (L.length vs) vs
+
+primArrayFromListN :: forall a. Prim a => Int -> [a] -> PrimArray a
+primArrayFromListN len vs = runST run where
+  run :: forall s. ST s (PrimArray a)
+  run = do
+    arr <- newPrimArray len
+    let go :: [a] -> Int -> ST s ()
+        go [] !ix = if ix == len
+          then return ()
+          else die "fromListN" "list length less than specified size"
+        go (a : as) !ix = if ix < len
+          then do
+            writePrimArray arr ix a
+            go as (ix + 1)
+          else die "fromListN" "list length greater than specified size"
+    go vs 0
+    unsafeFreezePrimArray arr
+
+-- | Convert the primitive array to a list.
+{-# INLINE primArrayToList #-}
+primArrayToList :: forall a. Prim a => PrimArray a -> [a]
+primArrayToList xs = build (\c n -> foldrPrimArray c n xs)
+
+primArrayToByteArray :: PrimArray a -> PB.ByteArray
+primArrayToByteArray (PrimArray x) = PB.ByteArray x
+
+byteArrayToPrimArray :: ByteArray -> PrimArray a
+byteArrayToPrimArray (PB.ByteArray x) = PrimArray x
+
+#if MIN_VERSION_base(4,9,0)
+-- | @since 0.6.4.0
+instance Semigroup (PrimArray a) where
+  x <> y = byteArrayToPrimArray (primArrayToByteArray x SG.<> primArrayToByteArray y)
+  sconcat = byteArrayToPrimArray . SG.sconcat . fmap primArrayToByteArray
+  stimes i arr = byteArrayToPrimArray (SG.stimes i (primArrayToByteArray arr))
+#endif
+
+-- | @since 0.6.4.0
+instance Monoid (PrimArray a) where
+  mempty = emptyPrimArray
+#if !(MIN_VERSION_base(4,11,0))
+  mappend x y = byteArrayToPrimArray (mappend (primArrayToByteArray x) (primArrayToByteArray y))
+#endif
+  mconcat = byteArrayToPrimArray . mconcat . map primArrayToByteArray
+
+-- | The empty primitive array.
+emptyPrimArray :: PrimArray a
+{-# NOINLINE emptyPrimArray #-}
+emptyPrimArray = runST $ primitive $ \s0# -> case newByteArray# 0# s0# of
+  (# s1#, arr# #) -> case unsafeFreezeByteArray# arr# s1# of
+    (# s2#, arr'# #) -> (# s2#, PrimArray arr'# #)
+
+-- | Create a new mutable primitive array of the given length. The
+-- underlying memory is left uninitialized.
+newPrimArray :: forall m a. (PrimMonad m, Prim a) => Int -> m (MutablePrimArray (PrimState m) a)
+{-# INLINE newPrimArray #-}
+newPrimArray (I# n#)
+  = primitive (\s# -> 
+      case newByteArray# (n# *# sizeOf# (undefined :: a)) s# of
+        (# s'#, arr# #) -> (# s'#, MutablePrimArray arr# #)
+    )
+
+-- | Resize a mutable primitive array. The new size is given in elements.
+--
+-- This will either resize the array in-place or, if not possible, allocate the
+-- contents into a new, unpinned array and copy the original array\'s contents.
+--
+-- To avoid undefined behaviour, the original 'MutablePrimArray' shall not be
+-- accessed anymore after a 'resizeMutablePrimArray' has been performed.
+-- Moreover, no reference to the old one should be kept in order to allow
+-- garbage collection of the original 'MutablePrimArray' in case a new
+-- 'MutablePrimArray' had to be allocated.
+resizeMutablePrimArray :: forall m a. (PrimMonad m, Prim a)
+  => MutablePrimArray (PrimState m) a
+  -> Int -- ^ new size
+  -> m (MutablePrimArray (PrimState m) a)
+{-# INLINE resizeMutablePrimArray #-}
+#if __GLASGOW_HASKELL__ >= 710
+resizeMutablePrimArray (MutablePrimArray arr#) (I# n#)
+  = primitive (\s# -> case resizeMutableByteArray# arr# (n# *# sizeOf# (undefined :: a)) s# of
+                        (# s'#, arr'# #) -> (# s'#, MutablePrimArray arr'# #))
+#else
+resizeMutablePrimArray arr n
+  = do arr' <- newPrimArray n
+       copyMutablePrimArray arr' 0 arr 0 (min (sizeofMutablePrimArray arr) n)
+       return arr'
+#endif
+
+-- Although it is possible to shim resizeMutableByteArray for old GHCs, this
+-- is not the case with shrinkMutablePrimArray.
+#if __GLASGOW_HASKELL__ >= 710
+-- | Shrink a mutable primitive array. The new size is given in elements.
+-- It must be smaller than the old size. The array will be resized in place.
+-- This function is only available when compiling with GHC 7.10 or newer.
+shrinkMutablePrimArray :: forall m a. (PrimMonad m, Prim a)
+  => MutablePrimArray (PrimState m) a
+  -> Int -- ^ new size
+  -> m ()
+{-# INLINE shrinkMutablePrimArray #-}
+shrinkMutablePrimArray (MutablePrimArray arr#) (I# n#)
+  = primitive_ (shrinkMutableByteArray# arr# (n# *# sizeOf# (undefined :: a)))
+#endif
+
+readPrimArray :: (Prim a, PrimMonad m) => MutablePrimArray (PrimState m) a -> Int -> m a
+{-# INLINE readPrimArray #-}
+readPrimArray (MutablePrimArray arr#) (I# i#)
+  = primitive (readByteArray# arr# i#)
+
+-- | Write an element to the given index.
+writePrimArray ::
+     (Prim a, PrimMonad m)
+  => MutablePrimArray (PrimState m) a -- ^ array
+  -> Int -- ^ index
+  -> a -- ^ element
+  -> m ()
+{-# INLINE writePrimArray #-}
+writePrimArray (MutablePrimArray arr#) (I# i#) x
+  = primitive_ (writeByteArray# arr# i# x)
+
+-- | Copy part of a mutable array into another mutable array.
+--   In the case that the destination and
+--   source arrays are the same, the regions may overlap.
+copyMutablePrimArray :: forall m a.
+     (PrimMonad m, Prim a)
+  => MutablePrimArray (PrimState m) a -- ^ destination array
+  -> Int -- ^ offset into destination array
+  -> MutablePrimArray (PrimState m) a -- ^ source array
+  -> Int -- ^ offset into source array
+  -> Int -- ^ number of elements to copy
+  -> m ()
+{-# INLINE copyMutablePrimArray #-}
+copyMutablePrimArray (MutablePrimArray dst#) (I# doff#) (MutablePrimArray src#) (I# soff#) (I# n#)
+  = primitive_ (copyMutableByteArray#
+      src# 
+      (soff# *# (sizeOf# (undefined :: a)))
+      dst#
+      (doff# *# (sizeOf# (undefined :: a)))
+      (n# *# (sizeOf# (undefined :: a)))
+    )
+
+-- | Copy part of an array into another mutable array.
+copyPrimArray :: forall m a.
+     (PrimMonad m, Prim a)
+  => MutablePrimArray (PrimState m) a -- ^ destination array
+  -> Int -- ^ offset into destination array
+  -> PrimArray a -- ^ source array
+  -> Int -- ^ offset into source array
+  -> Int -- ^ number of elements to copy
+  -> m ()
+{-# INLINE copyPrimArray #-}
+copyPrimArray (MutablePrimArray dst#) (I# doff#) (PrimArray src#) (I# soff#) (I# n#)
+  = primitive_ (copyByteArray#
+      src# 
+      (soff# *# (sizeOf# (undefined :: a)))
+      dst#
+      (doff# *# (sizeOf# (undefined :: a)))
+      (n# *# (sizeOf# (undefined :: a)))
+    )
+
+#if __GLASGOW_HASKELL__ >= 708
+-- | Copy a slice of an immutable primitive array to an address.
+--   The offset and length are given in elements of type @a@.
+--   This function assumes that the 'Prim' instance of @a@
+--   agrees with the 'Storable' instance. This function is only
+--   available when building with GHC 7.8 or newer.
+copyPrimArrayToPtr :: forall m a. (PrimMonad m, Prim a)
+  => Ptr a -- ^ destination pointer
+  -> PrimArray a -- ^ source array
+  -> Int -- ^ offset into source array
+  -> Int -- ^ number of prims to copy
+  -> m ()
+{-# INLINE copyPrimArrayToPtr #-}
+copyPrimArrayToPtr (Ptr addr#) (PrimArray ba#) (I# soff#) (I# n#) =
+    primitive (\ s# ->
+        let s'# = copyByteArrayToAddr# ba# (soff# *# siz#) addr# (n# *# siz#) s#
+        in (# s'#, () #))
+  where siz# = sizeOf# (undefined :: a)
+
+-- | Copy a slice of an immutable primitive array to an address.
+--   The offset and length are given in elements of type @a@.
+--   This function assumes that the 'Prim' instance of @a@
+--   agrees with the 'Storable' instance. This function is only
+--   available when building with GHC 7.8 or newer.
+copyMutablePrimArrayToPtr :: forall m a. (PrimMonad m, Prim a)
+  => Ptr a -- ^ destination pointer
+  -> MutablePrimArray (PrimState m) a -- ^ source array
+  -> Int -- ^ offset into source array
+  -> Int -- ^ number of prims to copy
+  -> m ()
+{-# INLINE copyMutablePrimArrayToPtr #-}
+copyMutablePrimArrayToPtr (Ptr addr#) (MutablePrimArray mba#) (I# soff#) (I# n#) =
+    primitive (\ s# ->
+        let s'# = copyMutableByteArrayToAddr# mba# (soff# *# siz#) addr# (n# *# siz#) s#
+        in (# s'#, () #))
+  where siz# = sizeOf# (undefined :: a)
+#endif
+
+-- | Fill a slice of a mutable primitive array with a value.
+setPrimArray
+  :: (Prim a, PrimMonad m)
+  => MutablePrimArray (PrimState m) a -- ^ array to fill
+  -> Int -- ^ offset into array
+  -> Int -- ^ number of values to fill
+  -> a -- ^ value to fill with
+  -> m ()
+{-# INLINE setPrimArray #-}
+setPrimArray (MutablePrimArray dst#) (I# doff#) (I# sz#) x
+  = primitive_ (PT.setByteArray# dst# doff# sz# x)
+
+-- | Get the size of a mutable primitive array in elements. Unlike 'sizeofMutablePrimArray',
+-- this function ensures sequencing in the presence of resizing.
+getSizeofMutablePrimArray :: forall m a. (PrimMonad m, Prim a)
+  => MutablePrimArray (PrimState m) a -- ^ array
+  -> m Int
+{-# INLINE getSizeofMutablePrimArray #-}
+#if __GLASGOW_HASKELL__ >= 801
+getSizeofMutablePrimArray (MutablePrimArray arr#)
+  = primitive (\s# -> 
+      case getSizeofMutableByteArray# arr# s# of
+        (# s'#, sz# #) -> (# s'#, I# (quotInt# sz# (sizeOf# (undefined :: a))) #)
+    )
+#else
+-- On older GHCs, it is not possible to resize a byte array, so
+-- this provides behavior consistent with the implementation for
+-- newer GHCs.
+getSizeofMutablePrimArray arr
+  = return (sizeofMutablePrimArray arr)
+#endif
+
+-- | Size of the mutable primitive array in elements. This function shall not
+--   be used on primitive arrays that are an argument to or a result of
+--   'resizeMutablePrimArray' or 'shrinkMutablePrimArray'.
+sizeofMutablePrimArray :: forall s a. Prim a => MutablePrimArray s a -> Int
+{-# INLINE sizeofMutablePrimArray #-}
+sizeofMutablePrimArray (MutablePrimArray arr#) =
+  I# (quotInt# (sizeofMutableByteArray# arr#) (sizeOf# (undefined :: a)))
+
+-- | Check if the two arrays refer to the same memory block.
+sameMutablePrimArray :: MutablePrimArray s a -> MutablePrimArray s a -> Bool
+{-# INLINE sameMutablePrimArray #-}
+sameMutablePrimArray (MutablePrimArray arr#) (MutablePrimArray brr#)
+  = isTrue# (sameMutableByteArray# arr# brr#)
+
+-- | Convert a mutable byte array to an immutable one without copying. The
+-- array should not be modified after the conversion.
+unsafeFreezePrimArray
+  :: PrimMonad m => MutablePrimArray (PrimState m) a -> m (PrimArray a)
+{-# INLINE unsafeFreezePrimArray #-}
+unsafeFreezePrimArray (MutablePrimArray arr#)
+  = primitive (\s# -> case unsafeFreezeByteArray# arr# s# of
+                        (# s'#, arr'# #) -> (# s'#, PrimArray arr'# #))
+
+-- | Convert an immutable array to a mutable one without copying. The
+-- original array should not be used after the conversion.
+unsafeThawPrimArray
+  :: PrimMonad m => PrimArray a -> m (MutablePrimArray (PrimState m) a)
+{-# INLINE unsafeThawPrimArray #-}
+unsafeThawPrimArray (PrimArray arr#)
+  = primitive (\s# -> (# s#, MutablePrimArray (unsafeCoerce# arr#) #))
+
+-- | Read a primitive value from the primitive array.
+indexPrimArray :: forall a. Prim a => PrimArray a -> Int -> a
+{-# INLINE indexPrimArray #-}
+indexPrimArray (PrimArray arr#) (I# i#) = indexByteArray# arr# i#
+
+-- | Get the size, in elements, of the primitive array.
+sizeofPrimArray :: forall a. Prim a => PrimArray a -> Int
+{-# INLINE sizeofPrimArray #-}
+sizeofPrimArray (PrimArray arr#) = I# (quotInt# (sizeofByteArray# arr#) (sizeOf# (undefined :: a)))
+
+-- | Lazy right-associated fold over the elements of a 'PrimArray'.
+{-# INLINE foldrPrimArray #-}
+foldrPrimArray :: forall a b. Prim a => (a -> b -> b) -> b -> PrimArray a -> b
+foldrPrimArray f z arr = go 0
+  where
+    !sz = sizeofPrimArray arr
+    go !i
+      | sz > i = f (indexPrimArray arr i) (go (i+1))
+      | otherwise = z
+
+-- | Strict right-associated fold over the elements of a 'PrimArray'.
+{-# INLINE foldrPrimArray' #-}
+foldrPrimArray' :: forall a b. Prim a => (a -> b -> b) -> b -> PrimArray a -> b
+foldrPrimArray' f z0 arr = go (sizeofPrimArray arr - 1) z0
+  where
+    go !i !acc
+      | i < 0 = acc
+      | otherwise = go (i - 1) (f (indexPrimArray arr i) acc)
+
+-- | Lazy left-associated fold over the elements of a 'PrimArray'.
+{-# INLINE foldlPrimArray #-}
+foldlPrimArray :: forall a b. Prim a => (b -> a -> b) -> b -> PrimArray a -> b
+foldlPrimArray f z arr = go (sizeofPrimArray arr - 1)
+  where
+    go !i
+      | i < 0 = z
+      | otherwise = f (go (i - 1)) (indexPrimArray arr i)
+
+-- | Strict left-associated fold over the elements of a 'PrimArray'.
+{-# INLINE foldlPrimArray' #-}
+foldlPrimArray' :: forall a b. Prim a => (b -> a -> b) -> b -> PrimArray a -> b
+foldlPrimArray' f z0 arr = go 0 z0
+  where
+    !sz = sizeofPrimArray arr
+    go !i !acc
+      | i < sz = go (i + 1) (f acc (indexPrimArray arr i))
+      | otherwise = acc
+
+-- | Strict left-associated fold over the elements of a 'PrimArray'.
+{-# INLINE foldlPrimArrayM' #-}
+foldlPrimArrayM' :: (Prim a, Monad m) => (b -> a -> m b) -> b -> PrimArray a -> m b
+foldlPrimArrayM' f z0 arr = go 0 z0
+  where
+    !sz = sizeofPrimArray arr
+    go !i !acc1
+      | i < sz = do
+          acc2 <- f acc1 (indexPrimArray arr i)
+          go (i + 1) acc2
+      | otherwise = return acc1
+
+-- | Traverse a primitive array. The traversal forces the resulting values and
+-- writes them to the new primitive array as it performs the monadic effects.
+-- Consequently:
+--
+-- >>> traversePrimArrayP (\x -> print x $> bool x undefined (x == 2)) (fromList [1, 2, 3 :: Int])
+-- 1
+-- 2
+-- *** Exception: Prelude.undefined
+--
+-- In many situations, 'traversePrimArrayP' can replace 'traversePrimArray',
+-- changing the strictness characteristics of the traversal but typically improving
+-- the performance. Consider the following short-circuiting traversal:
+--
+-- > incrPositiveA :: PrimArray Int -> Maybe (PrimArray Int)
+-- > incrPositiveA xs = traversePrimArray (\x -> bool Nothing (Just (x + 1)) (x > 0)) xs
+--
+-- This can be rewritten using 'traversePrimArrayP'. To do this, we must
+-- change the traversal context to @MaybeT (ST s)@, which has a 'PrimMonad'
+-- instance:
+--
+-- > incrPositiveB :: PrimArray Int -> Maybe (PrimArray Int)
+-- > incrPositiveB xs = runST $ runMaybeT $ traversePrimArrayP
+-- >   (\x -> bool (MaybeT (return Nothing)) (MaybeT (return (Just (x + 1)))) (x > 0))
+-- >   xs
+-- 
+-- Benchmarks demonstrate that the second implementation runs 150 times
+-- faster than the first. It also results in fewer allocations.
+{-# INLINE traversePrimArrayP #-}
+traversePrimArrayP :: (PrimMonad m, Prim a, Prim b)
+  => (a -> m b)
+  -> PrimArray a
+  -> m (PrimArray b)
+traversePrimArrayP f arr = do
+  let !sz = sizeofPrimArray arr
+  marr <- newPrimArray sz
+  let go !ix = if ix < sz
+        then do
+          b <- f (indexPrimArray arr ix)
+          writePrimArray marr ix b
+          go (ix + 1)
+        else return ()
+  go 0
+  unsafeFreezePrimArray marr
+
+-- | Filter the primitive array, keeping the elements for which the monadic
+-- predicate evaluates true.
+{-# INLINE filterPrimArrayP #-}
+filterPrimArrayP :: (PrimMonad m, Prim a)
+  => (a -> m Bool)
+  -> PrimArray a
+  -> m (PrimArray a)
+filterPrimArrayP f arr = do
+  let !sz = sizeofPrimArray arr
+  marr <- newPrimArray sz
+  let go !ixSrc !ixDst = if ixSrc < sz
+        then do
+          let a = indexPrimArray arr ixSrc
+          b <- f a
+          if b
+            then do
+              writePrimArray marr ixDst a
+              go (ixSrc + 1) (ixDst + 1)
+            else go (ixSrc + 1) ixDst
+        else return ixDst
+  lenDst <- go 0 0
+  marr' <- resizeMutablePrimArray marr lenDst
+  unsafeFreezePrimArray marr'
+
+-- | Map over the primitive array, keeping the elements for which the monadic
+-- predicate provides a 'Just'.
+{-# INLINE mapMaybePrimArrayP #-}
+mapMaybePrimArrayP :: (PrimMonad m, Prim a, Prim b)
+  => (a -> m (Maybe b))
+  -> PrimArray a
+  -> m (PrimArray b)
+mapMaybePrimArrayP f arr = do
+  let !sz = sizeofPrimArray arr
+  marr <- newPrimArray sz
+  let go !ixSrc !ixDst = if ixSrc < sz
+        then do
+          let a = indexPrimArray arr ixSrc
+          mb <- f a
+          case mb of
+            Just b -> do
+              writePrimArray marr ixDst b
+              go (ixSrc + 1) (ixDst + 1)
+            Nothing -> go (ixSrc + 1) ixDst
+        else return ixDst
+  lenDst <- go 0 0
+  marr' <- resizeMutablePrimArray marr lenDst
+  unsafeFreezePrimArray marr'
+
+-- | Generate a primitive array by evaluating the monadic generator function
+-- at each index.
+{-# INLINE generatePrimArrayP #-}
+generatePrimArrayP :: (PrimMonad m, Prim a)
+  => Int -- ^ length
+  -> (Int -> m a) -- ^ generator
+  -> m (PrimArray a)
+generatePrimArrayP sz f = do
+  marr <- newPrimArray sz
+  let go !ix = if ix < sz
+        then do
+          b <- f ix
+          writePrimArray marr ix b
+          go (ix + 1)
+        else return ()
+  go 0
+  unsafeFreezePrimArray marr
+
+-- | Execute the monadic action the given number of times and store the
+-- results in a primitive array.
+{-# INLINE replicatePrimArrayP #-}
+replicatePrimArrayP :: (PrimMonad m, Prim a)
+  => Int
+  -> m a
+  -> m (PrimArray a)
+replicatePrimArrayP sz f = do
+  marr <- newPrimArray sz
+  let go !ix = if ix < sz
+        then do
+          b <- f
+          writePrimArray marr ix b
+          go (ix + 1)
+        else return ()
+  go 0
+  unsafeFreezePrimArray marr
+
+
+-- | Map over the elements of a primitive array.
+{-# INLINE mapPrimArray #-}
+mapPrimArray :: (Prim a, Prim b)
+  => (a -> b)
+  -> PrimArray a
+  -> PrimArray b
+mapPrimArray f arr = runST $ do
+  let !sz = sizeofPrimArray arr
+  marr <- newPrimArray sz
+  let go !ix = if ix < sz
+        then do
+          let b = f (indexPrimArray arr ix)
+          writePrimArray marr ix b
+          go (ix + 1)
+        else return ()
+  go 0
+  unsafeFreezePrimArray marr
+
+-- | Indexed map over the elements of a primitive array.
+{-# INLINE imapPrimArray #-}
+imapPrimArray :: (Prim a, Prim b)
+  => (Int -> a -> b)
+  -> PrimArray a
+  -> PrimArray b
+imapPrimArray f arr = runST $ do
+  let !sz = sizeofPrimArray arr
+  marr <- newPrimArray sz
+  let go !ix = if ix < sz
+        then do
+          let b = f ix (indexPrimArray arr ix)
+          writePrimArray marr ix b
+          go (ix + 1)
+        else return ()
+  go 0
+  unsafeFreezePrimArray marr
+
+-- | Filter elements of a primitive array according to a predicate.
+{-# INLINE filterPrimArray #-}
+filterPrimArray :: Prim a
+  => (a -> Bool)
+  -> PrimArray a
+  -> PrimArray a
+filterPrimArray p arr = runST $ do
+  let !sz = sizeofPrimArray arr
+  marr <- newPrimArray sz
+  let go !ixSrc !ixDst = if ixSrc < sz
+        then do
+          let !a = indexPrimArray arr ixSrc
+          if p a
+            then do
+              writePrimArray marr ixDst a
+              go (ixSrc + 1) (ixDst + 1)
+            else go (ixSrc + 1) ixDst
+        else return ixDst
+  dstLen <- go 0 0
+  marr' <- resizeMutablePrimArray marr dstLen
+  unsafeFreezePrimArray marr'
+
+-- | Filter the primitive array, keeping the elements for which the monadic
+-- predicate evaluates true.
+filterPrimArrayA ::
+     (Applicative f, Prim a)
+  => (a -> f Bool) -- ^ mapping function
+  -> PrimArray a -- ^ primitive array
+  -> f (PrimArray a)
+filterPrimArrayA f = \ !ary ->
+  let
+    !len = sizeofPrimArray ary
+    go !ixSrc
+      | ixSrc == len = pure $ IxSTA $ \ixDst _ -> return ixDst
+      | otherwise = let x = indexPrimArray ary ixSrc in
+          liftA2
+            (\keep (IxSTA m) -> IxSTA $ \ixDst mary -> if keep
+              then writePrimArray (MutablePrimArray mary) ixDst x >> m (ixDst + 1) mary
+              else m ixDst mary
+            )
+            (f x)
+            (go (ixSrc + 1))
+  in if len == 0
+     then pure emptyPrimArray
+     else runIxSTA len <$> go 0
+
+-- | Map over the primitive array, keeping the elements for which the applicative
+-- predicate provides a 'Just'.
+mapMaybePrimArrayA ::
+     (Applicative f, Prim a, Prim b)
+  => (a -> f (Maybe b)) -- ^ mapping function
+  -> PrimArray a -- ^ primitive array
+  -> f (PrimArray b)
+mapMaybePrimArrayA f = \ !ary ->
+  let
+    !len = sizeofPrimArray ary
+    go !ixSrc
+      | ixSrc == len = pure $ IxSTA $ \ixDst _ -> return ixDst
+      | otherwise = let x = indexPrimArray ary ixSrc in
+          liftA2
+            (\mb (IxSTA m) -> IxSTA $ \ixDst mary -> case mb of
+              Just b -> writePrimArray (MutablePrimArray mary) ixDst b >> m (ixDst + 1) mary
+              Nothing -> m ixDst mary
+            )
+            (f x)
+            (go (ixSrc + 1))
+  in if len == 0
+     then pure emptyPrimArray
+     else runIxSTA len <$> go 0
+
+-- | Map over a primitive array, optionally discarding some elements. This
+--   has the same behavior as @Data.Maybe.mapMaybe@.
+{-# INLINE mapMaybePrimArray #-}
+mapMaybePrimArray :: (Prim a, Prim b)
+  => (a -> Maybe b)
+  -> PrimArray a
+  -> PrimArray b
+mapMaybePrimArray p arr = runST $ do
+  let !sz = sizeofPrimArray arr
+  marr <- newPrimArray sz
+  let go !ixSrc !ixDst = if ixSrc < sz
+        then do
+          let !a = indexPrimArray arr ixSrc
+          case p a of
+            Just b -> do
+              writePrimArray marr ixDst b
+              go (ixSrc + 1) (ixDst + 1)
+            Nothing -> go (ixSrc + 1) ixDst
+        else return ixDst
+  dstLen <- go 0 0
+  marr' <- resizeMutablePrimArray marr dstLen
+  unsafeFreezePrimArray marr'
+
+
+-- | Traverse a primitive array. The traversal performs all of the applicative
+-- effects /before/ forcing the resulting values and writing them to the new
+-- primitive array. Consequently:
+--
+-- >>> traversePrimArray (\x -> print x $> bool x undefined (x == 2)) (fromList [1, 2, 3 :: Int])
+-- 1
+-- 2
+-- 3
+-- *** Exception: Prelude.undefined
+--
+-- The function 'traversePrimArrayP' always outperforms this function, but it
+-- requires a 'PrimAffineMonad' constraint, and it forces the values as
+-- it performs the effects.
+traversePrimArray ::
+     (Applicative f, Prim a, Prim b)
+  => (a -> f b) -- ^ mapping function
+  -> PrimArray a -- ^ primitive array
+  -> f (PrimArray b)
+traversePrimArray f = \ !ary ->
+  let
+    !len = sizeofPrimArray ary
+    go !i
+      | i == len = pure $ STA $ \mary -> unsafeFreezePrimArray (MutablePrimArray mary)
+      | x <- indexPrimArray ary i
+      = liftA2 (\b (STA m) -> STA $ \mary ->
+                  writePrimArray (MutablePrimArray mary) i b >> m mary)
+               (f x) (go (i + 1))
+  in if len == 0
+     then pure emptyPrimArray
+     else runSTA len <$> go 0
+
+-- | Traverse a primitive array with the index of each element.
+itraversePrimArray ::
+     (Applicative f, Prim a, Prim b)
+  => (Int -> a -> f b)
+  -> PrimArray a
+  -> f (PrimArray b)
+itraversePrimArray f = \ !ary ->
+  let
+    !len = sizeofPrimArray ary
+    go !i
+      | i == len = pure $ STA $ \mary -> unsafeFreezePrimArray (MutablePrimArray mary)
+      | x <- indexPrimArray ary i
+      = liftA2 (\b (STA m) -> STA $ \mary ->
+                  writePrimArray (MutablePrimArray mary) i b >> m mary)
+               (f i x) (go (i + 1))
+  in if len == 0
+     then pure emptyPrimArray
+     else runSTA len <$> go 0
+
+-- | Traverse a primitive array with the indices. The traversal forces the
+-- resulting values and writes them to the new primitive array as it performs
+-- the monadic effects.
+{-# INLINE itraversePrimArrayP #-}
+itraversePrimArrayP :: (Prim a, Prim b, PrimMonad m)
+  => (Int -> a -> m b)
+  -> PrimArray a
+  -> m (PrimArray b)
+itraversePrimArrayP f arr = do
+  let !sz = sizeofPrimArray arr
+  marr <- newPrimArray sz
+  let go !ix
+        | ix < sz = do
+            writePrimArray marr ix =<< f ix (indexPrimArray arr ix)
+            go (ix + 1)
+        | otherwise = return ()
+  go 0
+  unsafeFreezePrimArray marr
+
+-- | Generate a primitive array.
+{-# INLINE generatePrimArray #-}
+generatePrimArray :: Prim a
+  => Int -- ^ length
+  -> (Int -> a) -- ^ element from index
+  -> PrimArray a
+generatePrimArray len f = runST $ do
+  marr <- newPrimArray len
+  let go !ix = if ix < len
+        then do
+          writePrimArray marr ix (f ix)
+          go (ix + 1)
+        else return ()
+  go 0
+  unsafeFreezePrimArray marr
+
+-- | Create a primitive array by copying the element the given
+-- number of times.
+{-# INLINE replicatePrimArray #-}
+replicatePrimArray :: Prim a
+  => Int -- ^ length
+  -> a -- ^ element
+  -> PrimArray a
+replicatePrimArray len a = runST $ do
+  marr <- newPrimArray len
+  setPrimArray marr 0 len a
+  unsafeFreezePrimArray marr
+
+-- | Generate a primitive array by evaluating the applicative generator
+-- function at each index.
+{-# INLINE generatePrimArrayA #-}
+generatePrimArrayA ::
+     (Applicative f, Prim a)
+  => Int -- ^ length
+  -> (Int -> f a) -- ^ element from index
+  -> f (PrimArray a)
+generatePrimArrayA len f =
+  let
+    go !i
+      | i == len = pure $ STA $ \mary -> unsafeFreezePrimArray (MutablePrimArray mary)
+      | otherwise
+      = liftA2 (\b (STA m) -> STA $ \mary ->
+                  writePrimArray (MutablePrimArray mary) i b >> m mary)
+               (f i) (go (i + 1))
+  in if len == 0
+     then pure emptyPrimArray
+     else runSTA len <$> go 0
+
+-- | Execute the applicative action the given number of times and store the
+-- results in a vector.
+{-# INLINE replicatePrimArrayA #-}
+replicatePrimArrayA ::
+     (Applicative f, Prim a)
+  => Int -- ^ length
+  -> f a -- ^ applicative element producer
+  -> f (PrimArray a)
+replicatePrimArrayA len f =
+  let
+    go !i
+      | i == len = pure $ STA $ \mary -> unsafeFreezePrimArray (MutablePrimArray mary)
+      | otherwise
+      = liftA2 (\b (STA m) -> STA $ \mary ->
+                  writePrimArray (MutablePrimArray mary) i b >> m mary)
+               f (go (i + 1))
+  in if len == 0
+     then pure emptyPrimArray
+     else runSTA len <$> go 0
+
+-- | Traverse the primitive array, discarding the results. There
+-- is no 'PrimMonad' variant of this function since it would not provide
+-- any performance benefit.
+traversePrimArray_ ::
+     (Applicative f, Prim a)
+  => (a -> f b)
+  -> PrimArray a
+  -> f ()
+traversePrimArray_ f a = go 0 where
+  !sz = sizeofPrimArray a
+  go !ix = if ix < sz
+    then f (indexPrimArray a ix) *> go (ix + 1)
+    else pure ()
+
+-- | Traverse the primitive array with the indices, discarding the results.
+-- There is no 'PrimMonad' variant of this function since it would not
+-- provide any performance benefit.
+itraversePrimArray_ ::
+     (Applicative f, Prim a)
+  => (Int -> a -> f b)
+  -> PrimArray a
+  -> f ()
+itraversePrimArray_ f a = go 0 where
+  !sz = sizeofPrimArray a
+  go !ix = if ix < sz
+    then f ix (indexPrimArray a ix) *> go (ix + 1)
+    else pure ()
+
+newtype IxSTA a = IxSTA {_runIxSTA :: forall s. Int -> MutableByteArray# s -> ST s Int}
+
+runIxSTA :: forall a. Prim a
+  => Int -- maximum possible size
+  -> IxSTA a
+  -> PrimArray a
+runIxSTA !szUpper = \ (IxSTA m) -> runST $ do
+  ar :: MutablePrimArray s a <- newPrimArray szUpper
+  sz <- m 0 (unMutablePrimArray ar)
+  ar' <- resizeMutablePrimArray ar sz
+  unsafeFreezePrimArray ar'
+{-# INLINE runIxSTA #-}
+
+newtype STA a = STA {_runSTA :: forall s. MutableByteArray# s -> ST s (PrimArray a)}
+
+runSTA :: forall a. Prim a => Int -> STA a -> PrimArray a
+runSTA !sz = \ (STA m) -> runST $ newPrimArray sz >>= \ (ar :: MutablePrimArray s a) -> m (unMutablePrimArray ar)
+{-# INLINE runSTA #-}
+
+unMutablePrimArray :: MutablePrimArray s a -> MutableByteArray# s
+unMutablePrimArray (MutablePrimArray m) = m
+
+{- $effectfulMapCreate
+The naming conventions adopted in this section are explained in the
+documentation of the @Data.Primitive@ module.
+-}
+
+

third_party/bazel/rules_haskell/examples/primitive/Data/Primitive/Ptr.hs

@@ -0,0 +1,125 @@
+{-# LANGUAGE CPP #-}
+{-# LANGUAGE MagicHash #-}
+{-# LANGUAGE UnboxedTuples #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+
+-- |
+-- Module      : Data.Primitive.Ptr
+-- Copyright   : (c) Roman Leshchinskiy 2009-2012
+-- License     : BSD-style
+--
+-- Maintainer  : Roman Leshchinskiy <rl@cse.unsw.edu.au>
+-- Portability : non-portable
+--
+-- Primitive operations on machine addresses
+--
+-- @since 0.6.4.0
+
+module Data.Primitive.Ptr (
+  -- * Types
+  Ptr(..),
+
+  -- * Address arithmetic
+  nullPtr, advancePtr, subtractPtr,
+
+  -- * Element access
+  indexOffPtr, readOffPtr, writeOffPtr,
+
+  -- * Block operations
+  copyPtr, movePtr, setPtr
+
+#if __GLASGOW_HASKELL__ >= 708
+  , copyPtrToMutablePrimArray
+#endif
+) where
+
+import Control.Monad.Primitive
+import Data.Primitive.Types
+#if __GLASGOW_HASKELL__ >= 708
+import Data.Primitive.PrimArray (MutablePrimArray(..))
+#endif
+
+import GHC.Base ( Int(..) )
+import GHC.Prim
+
+import GHC.Ptr
+import Foreign.Marshal.Utils
+
+
+-- | Offset a pointer by the given number of elements.
+advancePtr :: forall a. Prim a => Ptr a -> Int -> Ptr a
+{-# INLINE advancePtr #-}
+advancePtr (Ptr a#) (I# i#) = Ptr (plusAddr# a# (i# *# sizeOf# (undefined :: a)))
+
+-- | Subtract a pointer from another pointer. The result represents
+--   the number of elements of type @a@ that fit in the contiguous
+--   memory range bounded by these two pointers.
+subtractPtr :: forall a. Prim a => Ptr a -> Ptr a -> Int
+{-# INLINE subtractPtr #-}
+subtractPtr (Ptr a#) (Ptr b#) = I# (quotInt# (minusAddr# a# b#) (sizeOf# (undefined :: a)))
+
+-- | Read a value from a memory position given by a pointer and an offset.
+-- The memory block the address refers to must be immutable. The offset is in
+-- elements of type @a@ rather than in bytes.
+indexOffPtr :: Prim a => Ptr a -> Int -> a
+{-# INLINE indexOffPtr #-}
+indexOffPtr (Ptr addr#) (I# i#) = indexOffAddr# addr# i#
+
+-- | Read a value from a memory position given by an address and an offset.
+-- The offset is in elements of type @a@ rather than in bytes.
+readOffPtr :: (Prim a, PrimMonad m) => Ptr a -> Int -> m a
+{-# INLINE readOffPtr #-}
+readOffPtr (Ptr addr#) (I# i#) = primitive (readOffAddr# addr# i#)
+
+-- | Write a value to a memory position given by an address and an offset.
+-- The offset is in elements of type @a@ rather than in bytes.
+writeOffPtr :: (Prim a, PrimMonad m) => Ptr a -> Int -> a -> m ()
+{-# INLINE writeOffPtr #-}
+writeOffPtr (Ptr addr#) (I# i#) x = primitive_ (writeOffAddr# addr# i# x)
+
+-- | Copy the given number of elements from the second 'Ptr' to the first. The
+-- areas may not overlap.
+copyPtr :: forall m a. (PrimMonad m, Prim a)
+  => Ptr a -- ^ destination pointer
+  -> Ptr a -- ^ source pointer
+  -> Int -- ^ number of elements
+  -> m ()
+{-# INLINE copyPtr #-}
+copyPtr (Ptr dst#) (Ptr src#) n
+  = unsafePrimToPrim $ copyBytes (Ptr dst#) (Ptr src#) (n * sizeOf (undefined :: a))
+
+-- | Copy the given number of elements from the second 'Ptr' to the first. The
+-- areas may overlap.
+movePtr :: forall m a. (PrimMonad m, Prim a)
+  => Ptr a -- ^ destination address
+  -> Ptr a -- ^ source address
+  -> Int -- ^ number of elements
+  -> m ()
+{-# INLINE movePtr #-}
+movePtr (Ptr dst#) (Ptr src#) n
+  = unsafePrimToPrim $ moveBytes (Ptr dst#) (Ptr src#) (n * sizeOf (undefined :: a))
+
+-- | Fill a memory block with the given value. The length is in
+-- elements of type @a@ rather than in bytes.
+setPtr :: (Prim a, PrimMonad m) => Ptr a -> Int -> a -> m ()
+{-# INLINE setPtr #-}
+setPtr (Ptr addr#) (I# n#) x = primitive_ (setOffAddr# addr# 0# n# x)
+
+
+#if __GLASGOW_HASKELL__ >= 708
+-- | Copy from a pointer to a mutable primitive array.
+-- The offset and length are given in elements of type @a@.
+-- This function is only available when building with GHC 7.8
+-- or newer.
+copyPtrToMutablePrimArray :: forall m a. (PrimMonad m, Prim a)
+  => MutablePrimArray (PrimState m) a -- ^ destination array
+  -> Int -- ^ destination offset
+  -> Ptr a -- ^ source pointer
+  -> Int -- ^ number of elements
+  -> m ()
+{-# INLINE copyPtrToMutablePrimArray #-}
+copyPtrToMutablePrimArray (MutablePrimArray ba#) (I# doff#) (Ptr addr#) (I# n#) = 
+  primitive_ (copyAddrToByteArray# addr# ba# (doff# *# siz#) (n# *# siz#))
+  where
+  siz# = sizeOf# (undefined :: a)
+#endif

third_party/bazel/rules_haskell/examples/primitive/Data/Primitive/SmallArray.hs

@@ -0,0 +1,967 @@
+{-# LANGUAGE CPP #-}
+{-# LANGUAGE MagicHash #-}
+{-# LANGUAGE RankNTypes #-}
+{-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE UnboxedTuples #-}
+{-# LANGUAGE DeriveTraversable #-}
+{-# LANGUAGE DeriveDataTypeable #-}
+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
+{-# LANGUAGE BangPatterns #-}
+
+-- |
+-- Module : Data.Primitive.SmallArray
+-- Copyright: (c) 2015 Dan Doel
+-- License: BSD3
+--
+-- Maintainer: libraries@haskell.org
+-- Portability: non-portable
+--
+-- Small arrays are boxed (im)mutable arrays.
+--
+-- The underlying structure of the 'Array' type contains a card table, allowing
+-- segments of the array to be marked as having been mutated. This allows the
+-- garbage collector to only re-traverse segments of the array that have been
+-- marked during certain phases, rather than having to traverse the entire
+-- array.
+--
+-- 'SmallArray' lacks this table. This means that it takes up less memory and
+-- has slightly faster writes. It is also more efficient during garbage
+-- collection so long as the card table would have a single entry covering the
+-- entire array. These advantages make them suitable for use as arrays that are
+-- known to be small.
+--
+-- The card size is 128, so for uses much larger than that, 'Array' would likely
+-- be superior.
+--
+-- The underlying type, 'SmallArray#', was introduced in GHC 7.10, so prior to
+-- that version, this module simply implements small arrays as 'Array'.
+
+module Data.Primitive.SmallArray
+  ( SmallArray(..)
+  , SmallMutableArray(..)
+  , newSmallArray
+  , readSmallArray
+  , writeSmallArray
+  , copySmallArray
+  , copySmallMutableArray
+  , indexSmallArray
+  , indexSmallArrayM
+  , indexSmallArray##
+  , cloneSmallArray
+  , cloneSmallMutableArray
+  , freezeSmallArray
+  , unsafeFreezeSmallArray
+  , thawSmallArray
+  , runSmallArray
+  , unsafeThawSmallArray
+  , sizeofSmallArray
+  , sizeofSmallMutableArray
+  , smallArrayFromList
+  , smallArrayFromListN
+  , mapSmallArray'
+  , traverseSmallArrayP
+  ) where
+
+
+#if (__GLASGOW_HASKELL__ >= 710)
+#define HAVE_SMALL_ARRAY 1
+#endif
+
+#if MIN_VERSION_base(4,7,0)
+import GHC.Exts hiding (toList)
+import qualified GHC.Exts
+#endif
+
+import Control.Applicative
+import Control.Monad
+import Control.Monad.Fix
+import Control.Monad.Primitive
+import Control.Monad.ST
+import Control.Monad.Zip
+import Data.Data
+import Data.Foldable as Foldable
+import Data.Functor.Identity
+#if !(MIN_VERSION_base(4,10,0))
+import Data.Monoid
+#endif
+#if MIN_VERSION_base(4,9,0)
+import qualified GHC.ST as GHCST
+import qualified Data.Semigroup as Sem
+#endif
+import Text.ParserCombinators.ReadP
+#if MIN_VERSION_base(4,10,0)
+import GHC.Exts (runRW#)
+#elif MIN_VERSION_base(4,9,0)
+import GHC.Base (runRW#)
+#endif
+
+#if !(HAVE_SMALL_ARRAY)
+import Data.Primitive.Array
+import Data.Traversable
+import qualified Data.Primitive.Array as Array
+#endif
+
+#if MIN_VERSION_base(4,9,0) || MIN_VERSION_transformers(0,4,0)
+import Data.Functor.Classes (Eq1(..),Ord1(..),Show1(..),Read1(..))
+#endif
+
+#if HAVE_SMALL_ARRAY
+data SmallArray a = SmallArray (SmallArray# a)
+  deriving Typeable
+#else
+newtype SmallArray a = SmallArray (Array a) deriving
+  ( Eq
+  , Ord
+  , Show
+  , Read
+  , Foldable
+  , Traversable
+  , Functor
+  , Applicative
+  , Alternative
+  , Monad
+  , MonadPlus
+  , MonadZip
+  , MonadFix
+  , Monoid
+  , Typeable
+#if MIN_VERSION_base(4,9,0) || MIN_VERSION_transformers(0,4,0)
+  , Eq1
+  , Ord1
+  , Show1
+  , Read1
+#endif
+  )
+
+#if MIN_VERSION_base(4,7,0)
+instance IsList (SmallArray a) where
+  type Item (SmallArray a) = a
+  fromListN n l = SmallArray (fromListN n l)
+  fromList l = SmallArray (fromList l)
+  toList a = Foldable.toList a
+#endif
+#endif
+
+#if HAVE_SMALL_ARRAY
+data SmallMutableArray s a = SmallMutableArray (SmallMutableArray# s a)
+  deriving Typeable
+#else
+newtype SmallMutableArray s a = SmallMutableArray (MutableArray s a)
+  deriving (Eq, Typeable)
+#endif
+
+-- | Create a new small mutable array.
+newSmallArray
+  :: PrimMonad m
+  => Int -- ^ size
+  -> a   -- ^ initial contents
+  -> m (SmallMutableArray (PrimState m) a)
+#if HAVE_SMALL_ARRAY
+newSmallArray (I# i#) x = primitive $ \s ->
+  case newSmallArray# i# x s of
+    (# s', sma# #) -> (# s', SmallMutableArray sma# #)
+#else
+newSmallArray n e = SmallMutableArray `liftM` newArray n e
+#endif
+{-# INLINE newSmallArray #-}
+
+-- | Read the element at a given index in a mutable array.
+readSmallArray
+  :: PrimMonad m
+  => SmallMutableArray (PrimState m) a -- ^ array
+  -> Int                               -- ^ index
+  -> m a
+#if HAVE_SMALL_ARRAY
+readSmallArray (SmallMutableArray sma#) (I# i#) =
+  primitive $ readSmallArray# sma# i#
+#else
+readSmallArray (SmallMutableArray a) = readArray a
+#endif
+{-# INLINE readSmallArray #-}
+
+-- | Write an element at the given idex in a mutable array.
+writeSmallArray
+  :: PrimMonad m
+  => SmallMutableArray (PrimState m) a -- ^ array
+  -> Int                               -- ^ index
+  -> a                                 -- ^ new element
+  -> m ()
+#if HAVE_SMALL_ARRAY
+writeSmallArray (SmallMutableArray sma#) (I# i#) x =
+  primitive_ $ writeSmallArray# sma# i# x
+#else
+writeSmallArray (SmallMutableArray a) = writeArray a
+#endif
+{-# INLINE writeSmallArray #-}
+
+-- | Look up an element in an immutable array.
+--
+-- The purpose of returning a result using a monad is to allow the caller to
+-- avoid retaining references to the array. Evaluating the return value will
+-- cause the array lookup to be performed, even though it may not require the
+-- element of the array to be evaluated (which could throw an exception). For
+-- instance:
+--
+-- > data Box a = Box a
+-- > ...
+-- >
+-- > f sa = case indexSmallArrayM sa 0 of
+-- >   Box x -> ...
+--
+-- 'x' is not a closure that references 'sa' as it would be if we instead
+-- wrote:
+--
+-- > let x = indexSmallArray sa 0
+--
+-- And does not prevent 'sa' from being garbage collected.
+--
+-- Note that 'Identity' is not adequate for this use, as it is a newtype, and
+-- cannot be evaluated without evaluating the element.
+indexSmallArrayM
+  :: Monad m
+  => SmallArray a -- ^ array
+  -> Int          -- ^ index
+  -> m a
+#if HAVE_SMALL_ARRAY
+indexSmallArrayM (SmallArray sa#) (I# i#) =
+  case indexSmallArray# sa# i# of
+    (# x #) -> pure x
+#else
+indexSmallArrayM (SmallArray a) = indexArrayM a
+#endif
+{-# INLINE indexSmallArrayM #-}
+
+-- | Look up an element in an immutable array.
+indexSmallArray
+  :: SmallArray a -- ^ array
+  -> Int          -- ^ index
+  -> a
+#if HAVE_SMALL_ARRAY
+indexSmallArray sa i = runIdentity $ indexSmallArrayM sa i
+#else
+indexSmallArray (SmallArray a) = indexArray a
+#endif
+{-# INLINE indexSmallArray #-}
+
+-- | Read a value from the immutable array at the given index, returning
+-- the result in an unboxed unary tuple. This is currently used to implement
+-- folds.
+indexSmallArray## :: SmallArray a -> Int -> (# a #)
+#if HAVE_SMALL_ARRAY
+indexSmallArray## (SmallArray ary) (I# i) = indexSmallArray# ary i
+#else
+indexSmallArray## (SmallArray a) = indexArray## a
+#endif
+{-# INLINE indexSmallArray## #-}
+
+-- | Create a copy of a slice of an immutable array.
+cloneSmallArray
+  :: SmallArray a -- ^ source
+  -> Int          -- ^ offset
+  -> Int          -- ^ length
+  -> SmallArray a
+#if HAVE_SMALL_ARRAY
+cloneSmallArray (SmallArray sa#) (I# i#) (I# j#) =
+  SmallArray (cloneSmallArray# sa# i# j#)
+#else
+cloneSmallArray (SmallArray a) i j = SmallArray $ cloneArray a i j
+#endif
+{-# INLINE cloneSmallArray #-}
+
+-- | Create a copy of a slice of a mutable array.
+cloneSmallMutableArray
+  :: PrimMonad m
+  => SmallMutableArray (PrimState m) a -- ^ source
+  -> Int                               -- ^ offset
+  -> Int                               -- ^ length
+  -> m (SmallMutableArray (PrimState m) a)
+#if HAVE_SMALL_ARRAY
+cloneSmallMutableArray (SmallMutableArray sma#) (I# o#) (I# l#) =
+  primitive $ \s -> case cloneSmallMutableArray# sma# o# l# s of
+    (# s', smb# #) -> (# s', SmallMutableArray smb# #)
+#else
+cloneSmallMutableArray (SmallMutableArray ma) i j =
+  SmallMutableArray `liftM` cloneMutableArray ma i j
+#endif
+{-# INLINE cloneSmallMutableArray #-}
+
+-- | Create an immutable array corresponding to a slice of a mutable array.
+--
+-- This operation copies the portion of the array to be frozen.
+freezeSmallArray
+  :: PrimMonad m
+  => SmallMutableArray (PrimState m) a -- ^ source
+  -> Int                               -- ^ offset
+  -> Int                               -- ^ length
+  -> m (SmallArray a)
+#if HAVE_SMALL_ARRAY
+freezeSmallArray (SmallMutableArray sma#) (I# i#) (I# j#) =
+  primitive $ \s -> case freezeSmallArray# sma# i# j# s of
+    (# s', sa# #) -> (# s', SmallArray sa# #)
+#else
+freezeSmallArray (SmallMutableArray ma) i j =
+  SmallArray `liftM` freezeArray ma i j
+#endif
+{-# INLINE freezeSmallArray #-}
+
+-- | Render a mutable array immutable.
+--
+-- This operation performs no copying, so care must be taken not to modify the
+-- input array after freezing.
+unsafeFreezeSmallArray
+  :: PrimMonad m => SmallMutableArray (PrimState m) a -> m (SmallArray a)
+#if HAVE_SMALL_ARRAY
+unsafeFreezeSmallArray (SmallMutableArray sma#) =
+  primitive $ \s -> case unsafeFreezeSmallArray# sma# s of
+    (# s', sa# #) -> (# s', SmallArray sa# #)
+#else
+unsafeFreezeSmallArray (SmallMutableArray ma) =
+  SmallArray `liftM` unsafeFreezeArray ma
+#endif
+{-# INLINE unsafeFreezeSmallArray #-}
+
+-- | Create a mutable array corresponding to a slice of an immutable array.
+--
+-- This operation copies the portion of the array to be thawed.
+thawSmallArray
+  :: PrimMonad m
+  => SmallArray a -- ^ source
+  -> Int          -- ^ offset
+  -> Int          -- ^ length
+  -> m (SmallMutableArray (PrimState m) a)
+#if HAVE_SMALL_ARRAY
+thawSmallArray (SmallArray sa#) (I# o#) (I# l#) =
+  primitive $ \s -> case thawSmallArray# sa# o# l# s of
+    (# s', sma# #) -> (# s', SmallMutableArray sma# #)
+#else
+thawSmallArray (SmallArray a) off len =
+  SmallMutableArray `liftM` thawArray a off len
+#endif
+{-# INLINE thawSmallArray #-}
+
+-- | Render an immutable array mutable.
+--
+-- This operation performs no copying, so care must be taken with its use.
+unsafeThawSmallArray
+  :: PrimMonad m => SmallArray a -> m (SmallMutableArray (PrimState m) a)
+#if HAVE_SMALL_ARRAY
+unsafeThawSmallArray (SmallArray sa#) =
+  primitive $ \s -> case unsafeThawSmallArray# sa# s of
+    (# s', sma# #) -> (# s', SmallMutableArray sma# #)
+#else
+unsafeThawSmallArray (SmallArray a) = SmallMutableArray `liftM` unsafeThawArray a
+#endif
+{-# INLINE unsafeThawSmallArray #-}
+
+-- | Copy a slice of an immutable array into a mutable array.
+copySmallArray
+  :: PrimMonad m
+  => SmallMutableArray (PrimState m) a -- ^ destination
+  -> Int                               -- ^ destination offset
+  -> SmallArray a                      -- ^ source
+  -> Int                               -- ^ source offset
+  -> Int                               -- ^ length
+  -> m ()
+#if HAVE_SMALL_ARRAY
+copySmallArray
+  (SmallMutableArray dst#) (I# do#) (SmallArray src#) (I# so#) (I# l#) =
+    primitive_ $ copySmallArray# src# so# dst# do# l#
+#else
+copySmallArray (SmallMutableArray dst) i (SmallArray src) = copyArray dst i src
+#endif
+{-# INLINE copySmallArray #-}
+
+-- | Copy a slice of one mutable array into another.
+copySmallMutableArray
+  :: PrimMonad m
+  => SmallMutableArray (PrimState m) a -- ^ destination
+  -> Int                               -- ^ destination offset
+  -> SmallMutableArray (PrimState m) a -- ^ source
+  -> Int                               -- ^ source offset
+  -> Int                               -- ^ length
+  -> m ()
+#if HAVE_SMALL_ARRAY
+copySmallMutableArray
+  (SmallMutableArray dst#) (I# do#)
+  (SmallMutableArray src#) (I# so#)
+  (I# l#) =
+    primitive_ $ copySmallMutableArray# src# so# dst# do# l#
+#else
+copySmallMutableArray (SmallMutableArray dst) i (SmallMutableArray src) =
+  copyMutableArray dst i src
+#endif
+{-# INLINE copySmallMutableArray #-}
+
+sizeofSmallArray :: SmallArray a -> Int
+#if HAVE_SMALL_ARRAY
+sizeofSmallArray (SmallArray sa#) = I# (sizeofSmallArray# sa#)
+#else
+sizeofSmallArray (SmallArray a) = sizeofArray a
+#endif
+{-# INLINE sizeofSmallArray #-}
+
+sizeofSmallMutableArray :: SmallMutableArray s a -> Int
+#if HAVE_SMALL_ARRAY
+sizeofSmallMutableArray (SmallMutableArray sa#) =
+  I# (sizeofSmallMutableArray# sa#)
+#else
+sizeofSmallMutableArray (SmallMutableArray ma) = sizeofMutableArray ma
+#endif
+{-# INLINE sizeofSmallMutableArray #-}
+
+-- | This is the fastest, most straightforward way to traverse
+-- an array, but it only works correctly with a sufficiently
+-- "affine" 'PrimMonad' instance. In particular, it must only produce
+-- *one* result array. 'Control.Monad.Trans.List.ListT'-transformed
+-- monads, for example, will not work right at all.
+traverseSmallArrayP
+  :: PrimMonad m
+  => (a -> m b)
+  -> SmallArray a
+  -> m (SmallArray b)
+#if HAVE_SMALL_ARRAY
+traverseSmallArrayP f = \ !ary ->
+  let
+    !sz = sizeofSmallArray ary
+    go !i !mary
+      | i == sz
+      = unsafeFreezeSmallArray mary
+      | otherwise
+      = do
+          a <- indexSmallArrayM ary i
+          b <- f a
+          writeSmallArray mary i b
+          go (i + 1) mary
+  in do
+    mary <- newSmallArray sz badTraverseValue
+    go 0 mary
+#else
+traverseSmallArrayP f (SmallArray ar) = SmallArray `liftM` traverseArrayP f ar
+#endif
+{-# INLINE traverseSmallArrayP #-}
+
+-- | Strict map over the elements of the array.
+mapSmallArray' :: (a -> b) -> SmallArray a -> SmallArray b
+#if HAVE_SMALL_ARRAY
+mapSmallArray' f sa = createSmallArray (length sa) (die "mapSmallArray'" "impossible") $ \smb ->
+  fix ? 0 $ \go i ->
+    when (i < length sa) $ do
+      x <- indexSmallArrayM sa i
+      let !y = f x
+      writeSmallArray smb i y *> go (i+1)
+#else
+mapSmallArray' f (SmallArray ar) = SmallArray (mapArray' f ar)
+#endif
+{-# INLINE mapSmallArray' #-}
+
+#ifndef HAVE_SMALL_ARRAY
+runSmallArray
+  :: (forall s. ST s (SmallMutableArray s a))
+  -> SmallArray a
+runSmallArray m = SmallArray $ runArray $
+  m >>= \(SmallMutableArray mary) -> return mary
+
+#elif !MIN_VERSION_base(4,9,0)
+runSmallArray
+  :: (forall s. ST s (SmallMutableArray s a))
+  -> SmallArray a
+runSmallArray m = runST $ m >>= unsafeFreezeSmallArray
+
+#else
+-- This low-level business is designed to work with GHC's worker-wrapper
+-- transformation. A lot of the time, we don't actually need an Array
+-- constructor. By putting it on the outside, and being careful about
+-- how we special-case the empty array, we can make GHC smarter about this.
+-- The only downside is that separately created 0-length arrays won't share
+-- their Array constructors, although they'll share their underlying
+-- Array#s.
+runSmallArray
+  :: (forall s. ST s (SmallMutableArray s a))
+  -> SmallArray a
+runSmallArray m = SmallArray (runSmallArray# m)
+
+runSmallArray#
+  :: (forall s. ST s (SmallMutableArray s a))
+  -> SmallArray# a
+runSmallArray# m = case runRW# $ \s ->
+  case unST m s of { (# s', SmallMutableArray mary# #) ->
+  unsafeFreezeSmallArray# mary# s'} of (# _, ary# #) -> ary#
+
+unST :: ST s a -> State# s -> (# State# s, a #)
+unST (GHCST.ST f) = f
+
+#endif
+
+#if HAVE_SMALL_ARRAY
+-- See the comment on runSmallArray for why we use emptySmallArray#.
+createSmallArray
+  :: Int
+  -> a
+  -> (forall s. SmallMutableArray s a -> ST s ())
+  -> SmallArray a
+createSmallArray 0 _ _ = SmallArray (emptySmallArray# (# #))
+createSmallArray n x f = runSmallArray $ do
+  mary <- newSmallArray n x
+  f mary
+  pure mary
+
+emptySmallArray# :: (# #) -> SmallArray# a
+emptySmallArray# _ = case emptySmallArray of SmallArray ar -> ar
+{-# NOINLINE emptySmallArray# #-}
+
+die :: String -> String -> a
+die fun problem = error $ "Data.Primitive.SmallArray." ++ fun ++ ": " ++ problem
+
+emptySmallArray :: SmallArray a
+emptySmallArray =
+  runST $ newSmallArray 0 (die "emptySmallArray" "impossible")
+            >>= unsafeFreezeSmallArray
+{-# NOINLINE emptySmallArray #-}
+
+
+infixl 1 ?
+(?) :: (a -> b -> c) -> (b -> a -> c)
+(?) = flip
+{-# INLINE (?) #-}
+
+noOp :: a -> ST s ()
+noOp = const $ pure ()
+
+smallArrayLiftEq :: (a -> b -> Bool) -> SmallArray a -> SmallArray b -> Bool
+smallArrayLiftEq p sa1 sa2 = length sa1 == length sa2 && loop (length sa1 - 1)
+  where
+  loop i
+    | i < 0
+    = True
+    | (# x #) <- indexSmallArray## sa1 i
+    , (# y #) <- indexSmallArray## sa2 i
+    = p x y && loop (i-1)
+
+#if MIN_VERSION_base(4,9,0) || MIN_VERSION_transformers(0,4,0)
+-- | @since 0.6.4.0
+instance Eq1 SmallArray where
+#if MIN_VERSION_base(4,9,0) || MIN_VERSION_transformers(0,5,0)
+  liftEq = smallArrayLiftEq
+#else
+  eq1 = smallArrayLiftEq (==)
+#endif
+#endif
+
+instance Eq a => Eq (SmallArray a) where
+  sa1 == sa2 = smallArrayLiftEq (==) sa1 sa2
+
+instance Eq (SmallMutableArray s a) where
+  SmallMutableArray sma1# == SmallMutableArray sma2# =
+    isTrue# (sameSmallMutableArray# sma1# sma2#)
+
+smallArrayLiftCompare :: (a -> b -> Ordering) -> SmallArray a -> SmallArray b -> Ordering
+smallArrayLiftCompare elemCompare a1 a2 = loop 0
+  where
+  mn = length a1 `min` length a2
+  loop i
+    | i < mn
+    , (# x1 #) <- indexSmallArray## a1 i
+    , (# x2 #) <- indexSmallArray## a2 i
+    = elemCompare x1 x2 `mappend` loop (i+1)
+    | otherwise = compare (length a1) (length a2)
+
+#if MIN_VERSION_base(4,9,0) || MIN_VERSION_transformers(0,4,0)
+-- | @since 0.6.4.0
+instance Ord1 SmallArray where
+#if MIN_VERSION_base(4,9,0) || MIN_VERSION_transformers(0,5,0)
+  liftCompare = smallArrayLiftCompare
+#else
+  compare1 = smallArrayLiftCompare compare
+#endif
+#endif
+
+-- | Lexicographic ordering. Subject to change between major versions.
+instance Ord a => Ord (SmallArray a) where
+  compare sa1 sa2 = smallArrayLiftCompare compare sa1 sa2
+
+instance Foldable SmallArray where
+  -- Note: we perform the array lookups eagerly so we won't
+  -- create thunks to perform lookups even if GHC can't see
+  -- that the folding function is strict.
+  foldr f = \z !ary ->
+    let
+      !sz = sizeofSmallArray ary
+      go i
+        | i == sz = z
+        | (# x #) <- indexSmallArray## ary i
+        = f x (go (i+1))
+    in go 0
+  {-# INLINE foldr #-}
+  foldl f = \z !ary ->
+    let
+      go i
+        | i < 0 = z
+        | (# x #) <- indexSmallArray## ary i
+        = f (go (i-1)) x
+    in go (sizeofSmallArray ary - 1)
+  {-# INLINE foldl #-}
+  foldr1 f = \ !ary ->
+    let
+      !sz = sizeofSmallArray ary - 1
+      go i =
+        case indexSmallArray## ary i of
+          (# x #) | i == sz -> x
+                  | otherwise -> f x (go (i+1))
+    in if sz < 0
+       then die "foldr1" "Empty SmallArray"
+       else go 0
+  {-# INLINE foldr1 #-}
+  foldl1 f = \ !ary ->
+    let
+      !sz = sizeofSmallArray ary - 1
+      go i =
+        case indexSmallArray## ary i of
+          (# x #) | i == 0 -> x
+                  | otherwise -> f (go (i - 1)) x
+    in if sz < 0
+       then die "foldl1" "Empty SmallArray"
+       else go sz
+  {-# INLINE foldl1 #-}
+  foldr' f = \z !ary ->
+    let
+      go i !acc
+        | i == -1 = acc
+        | (# x #) <- indexSmallArray## ary i
+        = go (i-1) (f x acc)
+    in go (sizeofSmallArray ary - 1) z
+  {-# INLINE foldr' #-}
+  foldl' f = \z !ary ->
+    let
+      !sz = sizeofSmallArray ary
+      go i !acc
+        | i == sz = acc
+        | (# x #) <- indexSmallArray## ary i
+        = go (i+1) (f acc x)
+    in go 0 z
+  {-# INLINE foldl' #-}
+  null a = sizeofSmallArray a == 0
+  {-# INLINE null #-}
+  length = sizeofSmallArray
+  {-# INLINE length #-}
+  maximum ary | sz == 0   = die "maximum" "Empty SmallArray"
+              | (# frst #) <- indexSmallArray## ary 0
+              = go 1 frst
+   where
+     sz = sizeofSmallArray ary
+     go i !e
+       | i == sz = e
+       | (# x #) <- indexSmallArray## ary i
+       = go (i+1) (max e x)
+  {-# INLINE maximum #-}
+  minimum ary | sz == 0   = die "minimum" "Empty SmallArray"
+              | (# frst #) <- indexSmallArray## ary 0
+              = go 1 frst
+   where sz = sizeofSmallArray ary
+         go i !e
+           | i == sz = e
+           | (# x #) <- indexSmallArray## ary i
+           = go (i+1) (min e x)
+  {-# INLINE minimum #-}
+  sum = foldl' (+) 0
+  {-# INLINE sum #-}
+  product = foldl' (*) 1
+  {-# INLINE product #-}
+
+newtype STA a = STA {_runSTA :: forall s. SmallMutableArray# s a -> ST s (SmallArray a)}
+
+runSTA :: Int -> STA a -> SmallArray a
+runSTA !sz = \ (STA m) -> runST $ newSmallArray_ sz >>=
+                        \ (SmallMutableArray ar#) -> m ar#
+{-# INLINE runSTA #-}
+
+newSmallArray_ :: Int -> ST s (SmallMutableArray s a)
+newSmallArray_ !n = newSmallArray n badTraverseValue
+
+badTraverseValue :: a
+badTraverseValue = die "traverse" "bad indexing"
+{-# NOINLINE badTraverseValue #-}
+
+instance Traversable SmallArray where
+  traverse f = traverseSmallArray f
+  {-# INLINE traverse #-}
+
+traverseSmallArray
+  :: Applicative f
+  => (a -> f b) -> SmallArray a -> f (SmallArray b)
+traverseSmallArray f = \ !ary ->
+  let
+    !len = sizeofSmallArray ary
+    go !i
+      | i == len
+      = pure $ STA $ \mary -> unsafeFreezeSmallArray (SmallMutableArray mary)
+      | (# x #) <- indexSmallArray## ary i
+      = liftA2 (\b (STA m) -> STA $ \mary ->
+                  writeSmallArray (SmallMutableArray mary) i b >> m mary)
+               (f x) (go (i + 1))
+  in if len == 0
+     then pure emptySmallArray
+     else runSTA len <$> go 0
+{-# INLINE [1] traverseSmallArray #-}
+
+{-# RULES
+"traverse/ST" forall (f :: a -> ST s b). traverseSmallArray f = traverseSmallArrayP f
+"traverse/IO" forall (f :: a -> IO b). traverseSmallArray f = traverseSmallArrayP f
+"traverse/Id" forall (f :: a -> Identity b). traverseSmallArray f =
+   (coerce :: (SmallArray a -> SmallArray (Identity b))
+           -> SmallArray a -> Identity (SmallArray b)) (fmap f)
+ #-}
+
+
+instance Functor SmallArray where
+  fmap f sa = createSmallArray (length sa) (die "fmap" "impossible") $ \smb ->
+    fix ? 0 $ \go i ->
+      when (i < length sa) $ do
+        x <- indexSmallArrayM sa i
+        writeSmallArray smb i (f x) *> go (i+1)
+  {-# INLINE fmap #-}
+
+  x <$ sa = createSmallArray (length sa) x noOp
+
+instance Applicative SmallArray where
+  pure x = createSmallArray 1 x noOp
+
+  sa *> sb = createSmallArray (la*lb) (die "*>" "impossible") $ \smb ->
+    fix ? 0 $ \go i ->
+      when (i < la) $
+        copySmallArray smb 0 sb 0 lb *> go (i+1)
+   where
+   la = length sa ; lb = length sb
+
+  a <* b = createSmallArray (sza*szb) (die "<*" "impossible") $ \ma ->
+    let fill off i e = when (i < szb) $
+                         writeSmallArray ma (off+i) e >> fill off (i+1) e
+        go i = when (i < sza) $ do
+                 x <- indexSmallArrayM a i
+                 fill (i*szb) 0 x
+                 go (i+1)
+     in go 0
+   where sza = sizeofSmallArray a ; szb = sizeofSmallArray b
+
+  ab <*> a = createSmallArray (szab*sza) (die "<*>" "impossible") $ \mb ->
+    let go1 i = when (i < szab) $
+            do
+              f <- indexSmallArrayM ab i
+              go2 (i*sza) f 0
+              go1 (i+1)
+        go2 off f j = when (j < sza) $
+            do
+              x <- indexSmallArrayM a j
+              writeSmallArray mb (off + j) (f x)
+              go2 off f (j + 1)
+    in go1 0
+   where szab = sizeofSmallArray ab ; sza = sizeofSmallArray a
+
+instance Alternative SmallArray where
+  empty = emptySmallArray
+
+  sl <|> sr =
+    createSmallArray (length sl + length sr) (die "<|>" "impossible") $ \sma ->
+      copySmallArray sma 0 sl 0 (length sl)
+        *> copySmallArray sma (length sl) sr 0 (length sr)
+
+  many sa | null sa   = pure []
+          | otherwise = die "many" "infinite arrays are not well defined"
+
+  some sa | null sa   = emptySmallArray
+          | otherwise = die "some" "infinite arrays are not well defined"
+
+data ArrayStack a
+  = PushArray !(SmallArray a) !(ArrayStack a)
+  | EmptyStack
+-- TODO: This isn't terribly efficient. It would be better to wrap
+-- ArrayStack with a type like
+--
+-- data NES s a = NES !Int !(SmallMutableArray s a) !(ArrayStack a)
+--
+-- We'd copy incoming arrays into the mutable array until we would
+-- overflow it. Then we'd freeze it, push it on the stack, and continue.
+-- Any sufficiently large incoming arrays would go straight on the stack.
+-- Such a scheme would make the stack much more compact in the case
+-- of many small arrays.
+
+instance Monad SmallArray where
+  return = pure
+  (>>) = (*>)
+
+  sa >>= f = collect 0 EmptyStack (la-1)
+   where
+   la = length sa
+   collect sz stk i
+     | i < 0 = createSmallArray sz (die ">>=" "impossible") $ fill 0 stk
+     | (# x #) <- indexSmallArray## sa i
+     , let sb = f x
+           lsb = length sb
+       -- If we don't perform this check, we could end up allocating
+       -- a stack full of empty arrays if someone is filtering most
+       -- things out. So we refrain from pushing empty arrays.
+     = if lsb == 0
+       then collect sz stk (i-1)
+       else collect (sz + lsb) (PushArray sb stk) (i-1)
+
+   fill _ EmptyStack _ = return ()
+   fill off (PushArray sb sbs) smb =
+     copySmallArray smb off sb 0 (length sb)
+       *> fill (off + length sb) sbs smb
+
+  fail _ = emptySmallArray
+
+instance MonadPlus SmallArray where
+  mzero = empty
+  mplus = (<|>)
+
+zipW :: String -> (a -> b -> c) -> SmallArray a -> SmallArray b -> SmallArray c
+zipW nm = \f sa sb -> let mn = length sa `min` length sb in
+  createSmallArray mn (die nm "impossible") $ \mc ->
+    fix ? 0 $ \go i -> when (i < mn) $ do
+      x <- indexSmallArrayM sa i
+      y <- indexSmallArrayM sb i
+      writeSmallArray mc i (f x y)
+      go (i+1)
+{-# INLINE zipW #-}
+
+instance MonadZip SmallArray where
+  mzip = zipW "mzip" (,)
+  mzipWith = zipW "mzipWith"
+  {-# INLINE mzipWith #-}
+  munzip sab = runST $ do
+    let sz = length sab
+    sma <- newSmallArray sz $ die "munzip" "impossible"
+    smb <- newSmallArray sz $ die "munzip" "impossible"
+    fix ? 0 $ \go i ->
+      when (i < sz) $ case indexSmallArray sab i of
+        (x, y) -> do writeSmallArray sma i x
+                     writeSmallArray smb i y
+                     go $ i+1
+    (,) <$> unsafeFreezeSmallArray sma
+        <*> unsafeFreezeSmallArray smb
+
+instance MonadFix SmallArray where
+  mfix f = createSmallArray (sizeofSmallArray (f err))
+                            (die "mfix" "impossible") $ flip fix 0 $
+    \r !i !mary -> when (i < sz) $ do
+                      writeSmallArray mary i (fix (\xi -> f xi `indexSmallArray` i))
+                      r (i + 1) mary
+    where
+      sz = sizeofSmallArray (f err)
+      err = error "mfix for Data.Primitive.SmallArray applied to strict function."
+
+#if MIN_VERSION_base(4,9,0)
+-- | @since 0.6.3.0
+instance Sem.Semigroup (SmallArray a) where
+  (<>) = (<|>)
+  sconcat = mconcat . toList
+#endif
+
+instance Monoid (SmallArray a) where
+  mempty = empty
+#if !(MIN_VERSION_base(4,11,0))
+  mappend = (<|>)
+#endif
+  mconcat l = createSmallArray n (die "mconcat" "impossible") $ \ma ->
+    let go !_  [    ] = return ()
+        go off (a:as) =
+          copySmallArray ma off a 0 (sizeofSmallArray a) >> go (off + sizeofSmallArray a) as
+     in go 0 l
+   where n = sum . fmap length $ l
+
+instance IsList (SmallArray a) where
+  type Item (SmallArray a) = a
+  fromListN = smallArrayFromListN
+  fromList = smallArrayFromList
+  toList = Foldable.toList
+
+smallArrayLiftShowsPrec :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> Int -> SmallArray a -> ShowS
+smallArrayLiftShowsPrec elemShowsPrec elemListShowsPrec p sa = showParen (p > 10) $
+  showString "fromListN " . shows (length sa) . showString " "
+    . listLiftShowsPrec elemShowsPrec elemListShowsPrec 11 (toList sa)
+
+-- this need to be included for older ghcs
+listLiftShowsPrec :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> Int -> [a] -> ShowS
+listLiftShowsPrec _ sl _ = sl
+
+instance Show a => Show (SmallArray a) where
+  showsPrec p sa = smallArrayLiftShowsPrec showsPrec showList p sa
+
+#if MIN_VERSION_base(4,9,0) || MIN_VERSION_transformers(0,4,0)
+-- | @since 0.6.4.0
+instance Show1 SmallArray where
+#if MIN_VERSION_base(4,9,0) || MIN_VERSION_transformers(0,5,0)
+  liftShowsPrec = smallArrayLiftShowsPrec
+#else
+  showsPrec1 = smallArrayLiftShowsPrec showsPrec showList
+#endif
+#endif
+
+smallArrayLiftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (SmallArray a)
+smallArrayLiftReadsPrec _ listReadsPrec p = readParen (p > 10) . readP_to_S $ do
+  () <$ string "fromListN"
+  skipSpaces
+  n <- readS_to_P reads
+  skipSpaces
+  l <- readS_to_P listReadsPrec
+  return $ smallArrayFromListN n l
+
+instance Read a => Read (SmallArray a) where
+  readsPrec = smallArrayLiftReadsPrec readsPrec readList
+
+#if MIN_VERSION_base(4,9,0) || MIN_VERSION_transformers(0,4,0)
+-- | @since 0.6.4.0
+instance Read1 SmallArray where
+#if MIN_VERSION_base(4,9,0) || MIN_VERSION_transformers(0,5,0)
+  liftReadsPrec = smallArrayLiftReadsPrec
+#else
+  readsPrec1 = smallArrayLiftReadsPrec readsPrec readList
+#endif
+#endif
+
+
+
+smallArrayDataType :: DataType
+smallArrayDataType =
+  mkDataType "Data.Primitive.SmallArray.SmallArray" [fromListConstr]
+
+fromListConstr :: Constr
+fromListConstr = mkConstr smallArrayDataType "fromList" [] Prefix
+
+instance Data a => Data (SmallArray a) where
+  toConstr _ = fromListConstr
+  dataTypeOf _ = smallArrayDataType
+  gunfold k z c = case constrIndex c of
+    1 -> k (z fromList)
+    _ -> die "gunfold" "SmallArray"
+  gfoldl f z m = z fromList `f` toList m
+
+instance (Typeable s, Typeable a) => Data (SmallMutableArray s a) where
+  toConstr _ = die "toConstr" "SmallMutableArray"
+  gunfold _ _ = die "gunfold" "SmallMutableArray"
+  dataTypeOf _ = mkNoRepType "Data.Primitive.SmallArray.SmallMutableArray"
+#endif
+
+-- | Create a 'SmallArray' from a list of a known length. If the length
+--   of the list does not match the given length, this throws an exception.
+smallArrayFromListN :: Int -> [a] -> SmallArray a
+#if HAVE_SMALL_ARRAY
+smallArrayFromListN n l =
+  createSmallArray n
+      (die "smallArrayFromListN" "uninitialized element") $ \sma ->
+  let go !ix [] = if ix == n
+        then return ()
+        else die "smallArrayFromListN" "list length less than specified size"
+      go !ix (x : xs) = if ix < n
+        then do
+          writeSmallArray sma ix x
+          go (ix+1) xs
+        else die "smallArrayFromListN" "list length greater than specified size"
+  in go 0 l
+#else
+smallArrayFromListN n l = SmallArray (Array.fromListN n l)
+#endif
+
+-- | Create a 'SmallArray' from a list.
+smallArrayFromList :: [a] -> SmallArray a
+smallArrayFromList l = smallArrayFromListN (length l) l

third_party/bazel/rules_haskell/examples/primitive/Data/Primitive/Types.hs

@@ -0,0 +1,395 @@
+{-# LANGUAGE CPP, UnboxedTuples, MagicHash, DeriveDataTypeable #-}
+{-# LANGUAGE GeneralizedNewtypeDeriving, StandaloneDeriving #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+#if __GLASGOW_HASKELL__ >= 800
+{-# LANGUAGE TypeInType #-}
+#endif
+
+#include "HsBaseConfig.h"
+
+-- |
+-- Module      : Data.Primitive.Types
+-- Copyright   : (c) Roman Leshchinskiy 2009-2012
+-- License     : BSD-style
+--
+-- Maintainer  : Roman Leshchinskiy <rl@cse.unsw.edu.au>
+-- Portability : non-portable
+--
+-- Basic types and classes for primitive array operations
+--
+
+module Data.Primitive.Types (
+  Prim(..),
+  sizeOf, alignment, defaultSetByteArray#, defaultSetOffAddr#,
+
+  Addr(..),
+  PrimStorable(..)
+) where
+
+import Control.Monad.Primitive
+import Data.Primitive.MachDeps
+import Data.Primitive.Internal.Operations
+import Foreign.C.Types
+import System.Posix.Types
+
+import GHC.Base (
+    Int(..), Char(..),
+  )
+import GHC.Float (
+    Float(..), Double(..)
+  )
+import GHC.Word (
+    Word(..), Word8(..), Word16(..), Word32(..), Word64(..)
+  )
+import GHC.Int (
+    Int8(..), Int16(..), Int32(..), Int64(..)
+  )
+
+import GHC.Ptr (
+    Ptr(..), FunPtr(..)
+  )
+
+import GHC.Prim
+#if __GLASGOW_HASKELL__ >= 706
+    hiding (setByteArray#)
+#endif
+
+import Data.Typeable ( Typeable )
+import Data.Data ( Data(..) )
+import Data.Primitive.Internal.Compat ( isTrue#, mkNoRepType )
+import Foreign.Storable (Storable)
+import Numeric
+
+import qualified Foreign.Storable as FS
+
+-- | A machine address
+data Addr = Addr Addr# deriving ( Typeable )
+
+instance Show Addr where
+  showsPrec _ (Addr a) =
+    showString "0x" . showHex (fromIntegral (I# (addr2Int# a)) :: Word)
+
+instance Eq Addr where
+  Addr a# == Addr b# = isTrue# (eqAddr# a# b#)
+  Addr a# /= Addr b# = isTrue# (neAddr# a# b#)
+
+instance Ord Addr where
+  Addr a# > Addr b# = isTrue# (gtAddr# a# b#)
+  Addr a# >= Addr b# = isTrue# (geAddr# a# b#)
+  Addr a# < Addr b# = isTrue# (ltAddr# a# b#)
+  Addr a# <= Addr b# = isTrue# (leAddr# a# b#)
+
+instance Data Addr where
+  toConstr _ = error "toConstr"
+  gunfold _ _ = error "gunfold"
+  dataTypeOf _ = mkNoRepType "Data.Primitive.Types.Addr"
+
+
+-- | Class of types supporting primitive array operations
+class Prim a where
+
+  -- | Size of values of type @a@. The argument is not used.
+  sizeOf#    :: a -> Int#
+
+  -- | Alignment of values of type @a@. The argument is not used.
+  alignment# :: a -> Int#
+
+  -- | Read a value from the array. The offset is in elements of type
+  -- @a@ rather than in bytes.
+  indexByteArray# :: ByteArray# -> Int# -> a
+
+  -- | Read a value from the mutable array. The offset is in elements of type
+  -- @a@ rather than in bytes.
+  readByteArray# :: MutableByteArray# s -> Int# -> State# s -> (# State# s, a #)
+
+  -- | Write a value to the mutable array. The offset is in elements of type
+  -- @a@ rather than in bytes.
+  writeByteArray# :: MutableByteArray# s -> Int# -> a -> State# s -> State# s
+
+  -- | Fill a slice of the mutable array with a value. The offset and length
+  -- of the chunk are in elements of type @a@ rather than in bytes.
+  setByteArray# :: MutableByteArray# s -> Int# -> Int# -> a -> State# s -> State# s
+
+  -- | Read a value from a memory position given by an address and an offset.
+  -- The memory block the address refers to must be immutable. The offset is in
+  -- elements of type @a@ rather than in bytes.
+  indexOffAddr# :: Addr# -> Int# -> a
+
+  -- | Read a value from a memory position given by an address and an offset.
+  -- The offset is in elements of type @a@ rather than in bytes.
+  readOffAddr# :: Addr# -> Int# -> State# s -> (# State# s, a #)
+
+  -- | Write a value to a memory position given by an address and an offset.
+  -- The offset is in elements of type @a@ rather than in bytes.
+  writeOffAddr# :: Addr# -> Int# -> a -> State# s -> State# s
+
+  -- | Fill a memory block given by an address, an offset and a length.
+  -- The offset and length are in elements of type @a@ rather than in bytes.
+  setOffAddr# :: Addr# -> Int# -> Int# -> a -> State# s -> State# s
+
+-- | Size of values of type @a@. The argument is not used.
+--
+-- This function has existed since 0.1, but was moved from 'Data.Primitive'
+-- to 'Data.Primitive.Types' in version 0.6.3.0
+sizeOf :: Prim a => a -> Int
+sizeOf x = I# (sizeOf# x)
+
+-- | Alignment of values of type @a@. The argument is not used.
+--
+-- This function has existed since 0.1, but was moved from 'Data.Primitive'
+-- to 'Data.Primitive.Types' in version 0.6.3.0
+alignment :: Prim a => a -> Int
+alignment x = I# (alignment# x)
+
+-- | An implementation of 'setByteArray#' that calls 'writeByteArray#'
+-- to set each element. This is helpful when writing a 'Prim' instance
+-- for a multi-word data type for which there is no cpu-accelerated way
+-- to broadcast a value to contiguous memory. It is typically used
+-- alongside 'defaultSetOffAddr#'. For example:
+--
+-- > data Trip = Trip Int Int Int
+-- >
+-- > instance Prim Trip
+-- >   sizeOf# _ = 3# *# sizeOf# (undefined :: Int)
+-- >   alignment# _ = alignment# (undefined :: Int)
+-- >   indexByteArray# arr# i# = ...
+-- >   readByteArray# arr# i# = ...
+-- >   writeByteArray# arr# i# (Trip a b c) =
+-- >     \s0 -> case writeByteArray# arr# (3# *# i#) a s0 of
+-- >        s1 -> case writeByteArray# arr# ((3# *# i#) +# 1#) b s1 of
+-- >          s2 -> case writeByteArray# arr# ((3# *# i#) +# 2# ) c s2 of
+-- >            s3 -> s3
+-- >   setByteArray# = defaultSetByteArray#
+-- >   indexOffAddr# addr# i# = ...
+-- >   readOffAddr# addr# i# = ...
+-- >   writeOffAddr# addr# i# (Trip a b c) =
+-- >     \s0 -> case writeOffAddr# addr# (3# *# i#) a s0 of
+-- >        s1 -> case writeOffAddr# addr# ((3# *# i#) +# 1#) b s1 of
+-- >          s2 -> case writeOffAddr# addr# ((3# *# i#) +# 2# ) c s2 of
+-- >            s3 -> s3
+-- >   setOffAddr# = defaultSetOffAddr#
+defaultSetByteArray# :: Prim a => MutableByteArray# s -> Int# -> Int# -> a -> State# s -> State# s
+defaultSetByteArray# arr# i# len# ident = go 0#
+  where
+  go ix# s0 = if isTrue# (ix# <# len#)
+    then case writeByteArray# arr# (i# +# ix#) ident s0 of
+      s1 -> go (ix# +# 1#) s1
+    else s0
+
+-- | An implementation of 'setOffAddr#' that calls 'writeOffAddr#'
+-- to set each element. The documentation of 'defaultSetByteArray#'
+-- provides an example of how to use this.
+defaultSetOffAddr# :: Prim a => Addr# -> Int# -> Int# -> a -> State# s -> State# s
+defaultSetOffAddr# addr# i# len# ident = go 0#
+  where
+  go ix# s0 = if isTrue# (ix# <# len#)
+    then case writeOffAddr# addr# (i# +# ix#) ident s0 of
+      s1 -> go (ix# +# 1#) s1
+    else s0
+
+-- | Newtype that uses a 'Prim' instance to give rise to a 'Storable' instance.
+-- This type is intended to be used with the @DerivingVia@ extension available
+-- in GHC 8.6 and up. For example, consider a user-defined 'Prim' instance for
+-- a multi-word data type.
+--
+-- > data Uuid = Uuid Word64 Word64
+-- >   deriving Storable via (PrimStorable Uuid)
+-- > instance Prim Uuid where ...
+--
+-- Writing the 'Prim' instance is tedious and unavoidable, but the 'Storable'
+-- instance comes for free once the 'Prim' instance is written.
+newtype PrimStorable a = PrimStorable { getPrimStorable :: a }
+
+instance Prim a => Storable (PrimStorable a) where
+  sizeOf _ = sizeOf (undefined :: a)
+  alignment _ = alignment (undefined :: a)
+  peekElemOff (Ptr addr#) (I# i#) =
+    primitive $ \s0# -> case readOffAddr# addr# i# s0# of
+      (# s1, x #) -> (# s1, PrimStorable x #)
+  pokeElemOff (Ptr addr#) (I# i#) (PrimStorable a) = primitive_ $ \s# ->
+    writeOffAddr# addr# i# a s#
+
+#define derivePrim(ty, ctr, sz, align, idx_arr, rd_arr, wr_arr, set_arr, idx_addr, rd_addr, wr_addr, set_addr) \
+instance Prim (ty) where {                                      \
+  sizeOf# _ = unI# sz                                           \
+; alignment# _ = unI# align                                     \
+; indexByteArray# arr# i# = ctr (idx_arr arr# i#)               \
+; readByteArray#  arr# i# s# = case rd_arr arr# i# s# of        \
+                        { (# s1#, x# #) -> (# s1#, ctr x# #) }  \
+; writeByteArray# arr# i# (ctr x#) s# = wr_arr arr# i# x# s#    \
+; setByteArray# arr# i# n# (ctr x#) s#                          \
+    = let { i = fromIntegral (I# i#)                            \
+          ; n = fromIntegral (I# n#)                            \
+          } in                                                  \
+      case unsafeCoerce# (internal (set_arr arr# i n x#)) s# of \
+        { (# s1#, _ #) -> s1# }                                 \
+                                                                \
+; indexOffAddr# addr# i# = ctr (idx_addr addr# i#)              \
+; readOffAddr#  addr# i# s# = case rd_addr addr# i# s# of       \
+                        { (# s1#, x# #) -> (# s1#, ctr x# #) }  \
+; writeOffAddr# addr# i# (ctr x#) s# = wr_addr addr# i# x# s#   \
+; setOffAddr# addr# i# n# (ctr x#) s#                           \
+    = let { i = fromIntegral (I# i#)                            \
+          ; n = fromIntegral (I# n#)                            \
+          } in                                                  \
+      case unsafeCoerce# (internal (set_addr addr# i n x#)) s# of \
+        { (# s1#, _ #) -> s1# }                                 \
+; {-# INLINE sizeOf# #-}                                        \
+; {-# INLINE alignment# #-}                                     \
+; {-# INLINE indexByteArray# #-}                                \
+; {-# INLINE readByteArray# #-}                                 \
+; {-# INLINE writeByteArray# #-}                                \
+; {-# INLINE setByteArray# #-}                                  \
+; {-# INLINE indexOffAddr# #-}                                  \
+; {-# INLINE readOffAddr# #-}                                   \
+; {-# INLINE writeOffAddr# #-}                                  \
+; {-# INLINE setOffAddr# #-}                                    \
+}
+
+unI# :: Int -> Int#
+unI# (I# n#) = n#
+
+derivePrim(Word, W#, sIZEOF_WORD, aLIGNMENT_WORD,
+           indexWordArray#, readWordArray#, writeWordArray#, setWordArray#,
+           indexWordOffAddr#, readWordOffAddr#, writeWordOffAddr#, setWordOffAddr#)
+derivePrim(Word8, W8#, sIZEOF_WORD8, aLIGNMENT_WORD8,
+           indexWord8Array#, readWord8Array#, writeWord8Array#, setWord8Array#,
+           indexWord8OffAddr#, readWord8OffAddr#, writeWord8OffAddr#, setWord8OffAddr#)
+derivePrim(Word16, W16#, sIZEOF_WORD16, aLIGNMENT_WORD16,
+           indexWord16Array#, readWord16Array#, writeWord16Array#, setWord16Array#,
+           indexWord16OffAddr#, readWord16OffAddr#, writeWord16OffAddr#, setWord16OffAddr#)
+derivePrim(Word32, W32#, sIZEOF_WORD32, aLIGNMENT_WORD32,
+           indexWord32Array#, readWord32Array#, writeWord32Array#, setWord32Array#,
+           indexWord32OffAddr#, readWord32OffAddr#, writeWord32OffAddr#, setWord32OffAddr#)
+derivePrim(Word64, W64#, sIZEOF_WORD64, aLIGNMENT_WORD64,
+           indexWord64Array#, readWord64Array#, writeWord64Array#, setWord64Array#,
+           indexWord64OffAddr#, readWord64OffAddr#, writeWord64OffAddr#, setWord64OffAddr#)
+derivePrim(Int, I#, sIZEOF_INT, aLIGNMENT_INT,
+           indexIntArray#, readIntArray#, writeIntArray#, setIntArray#,
+           indexIntOffAddr#, readIntOffAddr#, writeIntOffAddr#, setIntOffAddr#)
+derivePrim(Int8, I8#, sIZEOF_INT8, aLIGNMENT_INT8,
+           indexInt8Array#, readInt8Array#, writeInt8Array#, setInt8Array#,
+           indexInt8OffAddr#, readInt8OffAddr#, writeInt8OffAddr#, setInt8OffAddr#)
+derivePrim(Int16, I16#, sIZEOF_INT16, aLIGNMENT_INT16,
+           indexInt16Array#, readInt16Array#, writeInt16Array#, setInt16Array#,
+           indexInt16OffAddr#, readInt16OffAddr#, writeInt16OffAddr#, setInt16OffAddr#)
+derivePrim(Int32, I32#, sIZEOF_INT32, aLIGNMENT_INT32,
+           indexInt32Array#, readInt32Array#, writeInt32Array#, setInt32Array#,
+           indexInt32OffAddr#, readInt32OffAddr#, writeInt32OffAddr#, setInt32OffAddr#)
+derivePrim(Int64, I64#, sIZEOF_INT64, aLIGNMENT_INT64,
+           indexInt64Array#, readInt64Array#, writeInt64Array#, setInt64Array#,
+           indexInt64OffAddr#, readInt64OffAddr#, writeInt64OffAddr#, setInt64OffAddr#)
+derivePrim(Float, F#, sIZEOF_FLOAT, aLIGNMENT_FLOAT,
+           indexFloatArray#, readFloatArray#, writeFloatArray#, setFloatArray#,
+           indexFloatOffAddr#, readFloatOffAddr#, writeFloatOffAddr#, setFloatOffAddr#)
+derivePrim(Double, D#, sIZEOF_DOUBLE, aLIGNMENT_DOUBLE,
+           indexDoubleArray#, readDoubleArray#, writeDoubleArray#, setDoubleArray#,
+           indexDoubleOffAddr#, readDoubleOffAddr#, writeDoubleOffAddr#, setDoubleOffAddr#)
+derivePrim(Char, C#, sIZEOF_CHAR, aLIGNMENT_CHAR,
+           indexWideCharArray#, readWideCharArray#, writeWideCharArray#, setWideCharArray#,
+           indexWideCharOffAddr#, readWideCharOffAddr#, writeWideCharOffAddr#, setWideCharOffAddr#)
+derivePrim(Addr, Addr, sIZEOF_PTR, aLIGNMENT_PTR,
+           indexAddrArray#, readAddrArray#, writeAddrArray#, setAddrArray#,
+           indexAddrOffAddr#, readAddrOffAddr#, writeAddrOffAddr#, setAddrOffAddr#)
+derivePrim(Ptr a, Ptr, sIZEOF_PTR, aLIGNMENT_PTR,
+           indexAddrArray#, readAddrArray#, writeAddrArray#, setAddrArray#,
+           indexAddrOffAddr#, readAddrOffAddr#, writeAddrOffAddr#, setAddrOffAddr#)
+derivePrim(FunPtr a, FunPtr, sIZEOF_PTR, aLIGNMENT_PTR,
+           indexAddrArray#, readAddrArray#, writeAddrArray#, setAddrArray#,
+           indexAddrOffAddr#, readAddrOffAddr#, writeAddrOffAddr#, setAddrOffAddr#)
+
+-- Prim instances for newtypes in Foreign.C.Types
+deriving instance Prim CChar
+deriving instance Prim CSChar
+deriving instance Prim CUChar
+deriving instance Prim CShort
+deriving instance Prim CUShort
+deriving instance Prim CInt
+deriving instance Prim CUInt
+deriving instance Prim CLong
+deriving instance Prim CULong
+deriving instance Prim CPtrdiff
+deriving instance Prim CSize
+deriving instance Prim CWchar
+deriving instance Prim CSigAtomic
+deriving instance Prim CLLong
+deriving instance Prim CULLong
+#if MIN_VERSION_base(4,10,0)
+deriving instance Prim CBool
+#endif
+deriving instance Prim CIntPtr
+deriving instance Prim CUIntPtr
+deriving instance Prim CIntMax
+deriving instance Prim CUIntMax
+deriving instance Prim CClock
+deriving instance Prim CTime
+deriving instance Prim CUSeconds
+deriving instance Prim CSUSeconds
+deriving instance Prim CFloat
+deriving instance Prim CDouble
+
+-- Prim instances for newtypes in System.Posix.Types
+#if defined(HTYPE_DEV_T)
+deriving instance Prim CDev
+#endif
+#if defined(HTYPE_INO_T)
+deriving instance Prim CIno
+#endif
+#if defined(HTYPE_MODE_T)
+deriving instance Prim CMode
+#endif
+#if defined(HTYPE_OFF_T)
+deriving instance Prim COff
+#endif
+#if defined(HTYPE_PID_T)
+deriving instance Prim CPid
+#endif
+#if defined(HTYPE_SSIZE_T)
+deriving instance Prim CSsize
+#endif
+#if defined(HTYPE_GID_T)
+deriving instance Prim CGid
+#endif
+#if defined(HTYPE_NLINK_T)
+deriving instance Prim CNlink
+#endif
+#if defined(HTYPE_UID_T)
+deriving instance Prim CUid
+#endif
+#if defined(HTYPE_CC_T)
+deriving instance Prim CCc
+#endif
+#if defined(HTYPE_SPEED_T)
+deriving instance Prim CSpeed
+#endif
+#if defined(HTYPE_TCFLAG_T)
+deriving instance Prim CTcflag
+#endif
+#if defined(HTYPE_RLIM_T)
+deriving instance Prim CRLim
+#endif
+#if defined(HTYPE_BLKSIZE_T)
+deriving instance Prim CBlkSize
+#endif
+#if defined(HTYPE_BLKCNT_T)
+deriving instance Prim CBlkCnt
+#endif
+#if defined(HTYPE_CLOCKID_T)
+deriving instance Prim CClockId
+#endif
+#if defined(HTYPE_FSBLKCNT_T)
+deriving instance Prim CFsBlkCnt
+#endif
+#if defined(HTYPE_FSFILCNT_T)
+deriving instance Prim CFsFilCnt
+#endif
+#if defined(HTYPE_ID_T)
+deriving instance Prim CId
+#endif
+#if defined(HTYPE_KEY_T)
+deriving instance Prim CKey
+#endif
+#if defined(HTYPE_TIMER_T)
+deriving instance Prim CTimer
+#endif
+deriving instance Prim Fd

third_party/bazel/rules_haskell/examples/primitive/Data/Primitive/UnliftedArray.hs

@@ -0,0 +1,638 @@
+{-# Language BangPatterns #-}
+{-# Language CPP #-}
+{-# Language DeriveDataTypeable #-}
+{-# Language MagicHash #-}
+{-# Language RankNTypes #-}
+{-# Language ScopedTypeVariables #-}
+{-# Language TypeFamilies #-}
+{-# Language UnboxedTuples #-}
+
+-- |
+-- Module      : Data.Primitive.UnliftedArray
+-- Copyright   : (c) Dan Doel 2016
+-- License     : BSD-style
+--
+-- Maintainer  : Libraries <libraries@haskell.org>
+-- Portability : non-portable
+--
+-- GHC contains three general classes of value types:
+--
+--   1. Unboxed types: values are machine values made up of fixed numbers of bytes
+--   2. Unlifted types: values are pointers, but strictly evaluated
+--   3. Lifted types: values are pointers, lazily evaluated
+--
+-- The first category can be stored in a 'ByteArray', and this allows types in
+-- category 3 that are simple wrappers around category 1 types to be stored
+-- more efficiently using a 'ByteArray'. This module provides the same facility
+-- for category 2 types.
+--
+-- GHC has two primitive types, 'ArrayArray#' and 'MutableArrayArray#'. These
+-- are arrays of pointers, but of category 2 values, so they are known to not
+-- be bottom. This allows types that are wrappers around such types to be stored
+-- in an array without an extra level of indirection.
+--
+-- The way that the 'ArrayArray#' API works is that one can read and write
+-- 'ArrayArray#' values to the positions. This works because all category 2
+-- types share a uniform representation, unlike unboxed values which are
+-- represented by varying (by type) numbers of bytes. However, using the
+-- this makes the internal API very unsafe to use, as one has to coerce values
+-- to and from 'ArrayArray#'.
+--
+-- The API presented by this module is more type safe. 'UnliftedArray' and
+-- 'MutableUnliftedArray' are parameterized by the type of arrays they contain, and
+-- the coercions necessary are abstracted into a class, 'PrimUnlifted', of things
+-- that are eligible to be stored.
+
+module Data.Primitive.UnliftedArray
+  ( -- * Types
+    UnliftedArray(..)
+  , MutableUnliftedArray(..)
+  , PrimUnlifted(..)
+    -- * Operations
+  , unsafeNewUnliftedArray
+  , newUnliftedArray
+  , setUnliftedArray
+  , sizeofUnliftedArray
+  , sizeofMutableUnliftedArray
+  , readUnliftedArray
+  , writeUnliftedArray
+  , indexUnliftedArray
+  , indexUnliftedArrayM
+  , unsafeFreezeUnliftedArray
+  , freezeUnliftedArray
+  , thawUnliftedArray
+  , runUnliftedArray
+  , sameMutableUnliftedArray
+  , copyUnliftedArray
+  , copyMutableUnliftedArray
+  , cloneUnliftedArray
+  , cloneMutableUnliftedArray
+    -- * List Conversion
+  , unliftedArrayToList
+  , unliftedArrayFromList
+  , unliftedArrayFromListN
+    -- * Folding
+  , foldrUnliftedArray
+  , foldrUnliftedArray'
+  , foldlUnliftedArray
+  , foldlUnliftedArray'
+    -- * Mapping
+  , mapUnliftedArray
+-- Missing operations:
+--  , unsafeThawUnliftedArray
+  ) where
+
+import Data.Typeable
+import Control.Applicative
+
+import GHC.Prim
+import GHC.Base (Int(..),build)
+
+import Control.Monad.Primitive
+
+import Control.Monad.ST (runST,ST)
+
+import Data.Monoid (Monoid,mappend)
+import Data.Primitive.Internal.Compat ( isTrue# )
+
+import qualified Data.List as L
+import           Data.Primitive.Array (Array)
+import qualified Data.Primitive.Array as A
+import           Data.Primitive.ByteArray (ByteArray)
+import qualified Data.Primitive.ByteArray as BA
+import qualified Data.Primitive.PrimArray as PA
+import qualified Data.Primitive.SmallArray as SA
+import qualified Data.Primitive.MutVar as MV
+import qualified Data.Monoid
+import qualified GHC.MVar as GM (MVar(..))
+import qualified GHC.Conc as GC (TVar(..))
+import qualified GHC.Stable as GSP (StablePtr(..))
+import qualified GHC.Weak as GW (Weak(..))
+import qualified GHC.Conc.Sync as GCS (ThreadId(..))
+import qualified GHC.Exts as E
+import qualified GHC.ST as GHCST
+
+#if MIN_VERSION_base(4,9,0)
+import Data.Semigroup (Semigroup)
+import qualified Data.Semigroup
+#endif
+
+#if MIN_VERSION_base(4,10,0)
+import GHC.Exts (runRW#)
+#elif MIN_VERSION_base(4,9,0)
+import GHC.Base (runRW#)
+#endif
+
+-- | Immutable arrays that efficiently store types that are simple wrappers
+-- around unlifted primitive types. The values of the unlifted type are
+-- stored directly, eliminating a layer of indirection.
+data UnliftedArray e = UnliftedArray ArrayArray#
+  deriving (Typeable)
+
+-- | Mutable arrays that efficiently store types that are simple wrappers
+-- around unlifted primitive types. The values of the unlifted type are
+-- stored directly, eliminating a layer of indirection.
+data MutableUnliftedArray s e = MutableUnliftedArray (MutableArrayArray# s)
+  deriving (Typeable)
+
+-- | Classifies the types that are able to be stored in 'UnliftedArray' and
+-- 'MutableUnliftedArray'. These should be types that are just liftings of the
+-- unlifted pointer types, so that their internal contents can be safely coerced
+-- into an 'ArrayArray#'.
+class PrimUnlifted a where
+  toArrayArray# :: a -> ArrayArray#
+  fromArrayArray# :: ArrayArray# -> a
+
+instance PrimUnlifted (UnliftedArray e) where
+  toArrayArray# (UnliftedArray aa#) = aa#
+  fromArrayArray# aa# = UnliftedArray aa#
+
+instance PrimUnlifted (MutableUnliftedArray s e) where
+  toArrayArray# (MutableUnliftedArray maa#) = unsafeCoerce# maa#
+  fromArrayArray# aa# = MutableUnliftedArray (unsafeCoerce# aa#)
+
+instance PrimUnlifted (Array a) where
+  toArrayArray# (A.Array a#) = unsafeCoerce# a#
+  fromArrayArray# aa# = A.Array (unsafeCoerce# aa#)
+
+instance PrimUnlifted (A.MutableArray s a) where
+  toArrayArray# (A.MutableArray ma#) = unsafeCoerce# ma#
+  fromArrayArray# aa# = A.MutableArray (unsafeCoerce# aa#)
+
+instance PrimUnlifted ByteArray where
+  toArrayArray# (BA.ByteArray ba#) = unsafeCoerce# ba#
+  fromArrayArray# aa# = BA.ByteArray (unsafeCoerce# aa#)
+
+instance PrimUnlifted (BA.MutableByteArray s) where
+  toArrayArray# (BA.MutableByteArray mba#) = unsafeCoerce# mba#
+  fromArrayArray# aa# = BA.MutableByteArray (unsafeCoerce# aa#)
+
+-- | @since 0.6.4.0
+instance PrimUnlifted (PA.PrimArray a) where
+  toArrayArray# (PA.PrimArray ba#) = unsafeCoerce# ba#
+  fromArrayArray# aa# = PA.PrimArray (unsafeCoerce# aa#)
+
+-- | @since 0.6.4.0
+instance PrimUnlifted (PA.MutablePrimArray s a) where
+  toArrayArray# (PA.MutablePrimArray mba#) = unsafeCoerce# mba#
+  fromArrayArray# aa# = PA.MutablePrimArray (unsafeCoerce# aa#)
+
+instance PrimUnlifted (SA.SmallArray a) where
+  toArrayArray# (SA.SmallArray sa#) = unsafeCoerce# sa#
+  fromArrayArray# aa# = SA.SmallArray (unsafeCoerce# aa#)
+
+instance PrimUnlifted (SA.SmallMutableArray s a) where
+  toArrayArray# (SA.SmallMutableArray sma#) = unsafeCoerce# sma#
+  fromArrayArray# aa# = SA.SmallMutableArray (unsafeCoerce# aa#)
+
+instance PrimUnlifted (MV.MutVar s a) where
+  toArrayArray# (MV.MutVar mv#) = unsafeCoerce# mv#
+  fromArrayArray# aa# = MV.MutVar (unsafeCoerce# aa#)
+
+-- | @since 0.6.4.0
+instance PrimUnlifted (GM.MVar a) where
+  toArrayArray# (GM.MVar mv#) = unsafeCoerce# mv#
+  fromArrayArray# mv# = GM.MVar (unsafeCoerce# mv#)
+
+-- | @since 0.6.4.0
+instance PrimUnlifted (GC.TVar a) where
+  toArrayArray# (GC.TVar tv#) = unsafeCoerce# tv#
+  fromArrayArray# tv# = GC.TVar (unsafeCoerce# tv#)
+
+-- | @since 0.6.4.0
+instance PrimUnlifted (GSP.StablePtr a) where
+  toArrayArray# (GSP.StablePtr tv#) = unsafeCoerce# tv#
+  fromArrayArray# tv# = GSP.StablePtr (unsafeCoerce# tv#)
+
+-- | @since 0.6.4.0
+instance PrimUnlifted (GW.Weak a) where
+  toArrayArray# (GW.Weak tv#) = unsafeCoerce# tv#
+  fromArrayArray# tv# = GW.Weak (unsafeCoerce# tv#)
+
+-- | @since 0.6.4.0
+instance PrimUnlifted GCS.ThreadId where
+  toArrayArray# (GCS.ThreadId tv#) = unsafeCoerce# tv#
+  fromArrayArray# tv# = GCS.ThreadId (unsafeCoerce# tv#)
+
+die :: String -> String -> a
+die fun problem = error $ "Data.Primitive.UnliftedArray." ++ fun ++ ": " ++ problem
+
+-- | Creates a new 'MutableUnliftedArray'. This function is unsafe because it
+-- initializes all elements of the array as pointers to the array itself. Attempting
+-- to read one of these elements before writing to it is in effect an unsafe
+-- coercion from the @MutableUnliftedArray s a@ to the element type.
+unsafeNewUnliftedArray
+  :: (PrimMonad m)
+  => Int -- ^ size
+  -> m (MutableUnliftedArray (PrimState m) a)
+unsafeNewUnliftedArray (I# i#) = primitive $ \s -> case newArrayArray# i# s of
+  (# s', maa# #) -> (# s', MutableUnliftedArray maa# #)
+{-# inline unsafeNewUnliftedArray #-}
+
+-- | Sets all the positions in an unlifted array to the designated value.
+setUnliftedArray
+  :: (PrimMonad m, PrimUnlifted a)
+  => MutableUnliftedArray (PrimState m) a -- ^ destination
+  -> a -- ^ value to fill with
+  -> m ()
+setUnliftedArray mua v = loop $ sizeofMutableUnliftedArray mua - 1
+ where
+ loop i | i < 0     = return ()
+        | otherwise = writeUnliftedArray mua i v >> loop (i-1)
+{-# inline setUnliftedArray #-}
+
+-- | Creates a new 'MutableUnliftedArray' with the specified value as initial
+-- contents. This is slower than 'unsafeNewUnliftedArray', but safer.
+newUnliftedArray
+  :: (PrimMonad m, PrimUnlifted a)
+  => Int -- ^ size
+  -> a -- ^ initial value
+  -> m (MutableUnliftedArray (PrimState m) a)
+newUnliftedArray len v =
+  unsafeNewUnliftedArray len >>= \mua -> setUnliftedArray mua v >> return mua
+{-# inline newUnliftedArray #-}
+
+-- | Yields the length of an 'UnliftedArray'.
+sizeofUnliftedArray :: UnliftedArray e -> Int
+sizeofUnliftedArray (UnliftedArray aa#) = I# (sizeofArrayArray# aa#)
+{-# inline sizeofUnliftedArray #-}
+
+-- | Yields the length of a 'MutableUnliftedArray'.
+sizeofMutableUnliftedArray :: MutableUnliftedArray s e -> Int
+sizeofMutableUnliftedArray (MutableUnliftedArray maa#)
+  = I# (sizeofMutableArrayArray# maa#)
+{-# inline sizeofMutableUnliftedArray #-}
+
+-- Internal indexing function.
+--
+-- Note: ArrayArray# is strictly evaluated, so this should have similar
+-- consequences to indexArray#, where matching on the unboxed single causes the
+-- array access to happen.
+indexUnliftedArrayU
+  :: PrimUnlifted a
+  => UnliftedArray a
+  -> Int
+  -> (# a #)
+indexUnliftedArrayU (UnliftedArray src#) (I# i#)
+  = case indexArrayArrayArray# src# i# of
+      aa# -> (# fromArrayArray# aa# #)
+{-# inline indexUnliftedArrayU #-}
+
+-- | Gets the value at the specified position of an 'UnliftedArray'.
+indexUnliftedArray
+  :: PrimUnlifted a
+  => UnliftedArray a -- ^ source
+  -> Int -- ^ index
+  -> a
+indexUnliftedArray ua i
+  = case indexUnliftedArrayU ua i of (# v #) -> v
+{-# inline indexUnliftedArray #-}
+
+-- | Gets the value at the specified position of an 'UnliftedArray'.
+-- The purpose of the 'Monad' is to allow for being eager in the
+-- 'UnliftedArray' value without having to introduce a data dependency
+-- directly on the result value.
+--
+-- It should be noted that this is not as much of a problem as with a normal
+-- 'Array', because elements of an 'UnliftedArray' are guaranteed to not
+-- be exceptional. This function is provided in case it is more desirable
+-- than being strict in the result value.
+indexUnliftedArrayM
+  :: (PrimUnlifted a, Monad m)
+  => UnliftedArray a -- ^ source
+  -> Int -- ^ index
+  -> m a
+indexUnliftedArrayM ua i
+  = case indexUnliftedArrayU ua i of
+      (# v #) -> return v
+{-# inline indexUnliftedArrayM #-}
+
+-- | Gets the value at the specified position of a 'MutableUnliftedArray'.
+readUnliftedArray
+  :: (PrimMonad m, PrimUnlifted a)
+  => MutableUnliftedArray (PrimState m) a -- ^ source
+  -> Int -- ^ index
+  -> m a
+readUnliftedArray (MutableUnliftedArray maa#) (I# i#)
+  = primitive $ \s -> case readArrayArrayArray# maa# i# s of
+      (# s', aa# #) -> (# s',  fromArrayArray# aa# #)
+{-# inline readUnliftedArray #-}
+
+-- | Sets the value at the specified position of a 'MutableUnliftedArray'.
+writeUnliftedArray
+  :: (PrimMonad m, PrimUnlifted a)
+  => MutableUnliftedArray (PrimState m) a -- ^ destination
+  -> Int -- ^ index
+  -> a -- ^ value
+  -> m ()
+writeUnliftedArray (MutableUnliftedArray maa#) (I# i#) a
+  = primitive_ (writeArrayArrayArray# maa# i# (toArrayArray# a))
+{-# inline writeUnliftedArray #-}
+
+-- | Freezes a 'MutableUnliftedArray', yielding an 'UnliftedArray'. This simply
+-- marks the array as frozen in place, so it should only be used when no further
+-- modifications to the mutable array will be performed.
+unsafeFreezeUnliftedArray
+  :: (PrimMonad m)
+  => MutableUnliftedArray (PrimState m) a
+  -> m (UnliftedArray a)
+unsafeFreezeUnliftedArray (MutableUnliftedArray maa#)
+  = primitive $ \s -> case unsafeFreezeArrayArray# maa# s of
+      (# s', aa# #) -> (# s', UnliftedArray aa# #)
+{-# inline unsafeFreezeUnliftedArray #-}
+
+-- | Determines whether two 'MutableUnliftedArray' values are the same. This is
+-- object/pointer identity, not based on the contents.
+sameMutableUnliftedArray
+  :: MutableUnliftedArray s a
+  -> MutableUnliftedArray s a
+  -> Bool
+sameMutableUnliftedArray (MutableUnliftedArray maa1#) (MutableUnliftedArray maa2#)
+  = isTrue# (sameMutableArrayArray# maa1# maa2#)
+{-# inline sameMutableUnliftedArray #-}
+
+-- | Copies the contents of an immutable array into a mutable array.
+copyUnliftedArray
+  :: (PrimMonad m)
+  => MutableUnliftedArray (PrimState m) a -- ^ destination
+  -> Int -- ^ offset into destination
+  -> UnliftedArray a -- ^ source
+  -> Int -- ^ offset into source
+  -> Int -- ^ number of elements to copy
+  -> m ()
+copyUnliftedArray
+  (MutableUnliftedArray dst) (I# doff)
+  (UnliftedArray src) (I# soff) (I# ln) =
+    primitive_ $ copyArrayArray# src soff dst doff ln
+{-# inline copyUnliftedArray #-}
+
+-- | Copies the contents of one mutable array into another.
+copyMutableUnliftedArray
+  :: (PrimMonad m)
+  => MutableUnliftedArray (PrimState m) a -- ^ destination
+  -> Int -- ^ offset into destination
+  -> MutableUnliftedArray (PrimState m) a -- ^ source
+  -> Int -- ^ offset into source
+  -> Int -- ^ number of elements to copy
+  -> m ()
+copyMutableUnliftedArray
+  (MutableUnliftedArray dst) (I# doff)
+  (MutableUnliftedArray src) (I# soff) (I# ln) =
+    primitive_ $ copyMutableArrayArray# src soff dst doff ln
+{-# inline copyMutableUnliftedArray #-}
+
+-- | Freezes a portion of a 'MutableUnliftedArray', yielding an 'UnliftedArray'.
+-- This operation is safe, in that it copies the frozen portion, and the
+-- existing mutable array may still be used afterward.
+freezeUnliftedArray
+  :: (PrimMonad m)
+  => MutableUnliftedArray (PrimState m) a -- ^ source
+  -> Int -- ^ offset
+  -> Int -- ^ length
+  -> m (UnliftedArray a)
+freezeUnliftedArray src off len = do
+  dst <- unsafeNewUnliftedArray len
+  copyMutableUnliftedArray dst 0 src off len
+  unsafeFreezeUnliftedArray dst
+{-# inline freezeUnliftedArray #-}
+
+-- | Thaws a portion of an 'UnliftedArray', yielding a 'MutableUnliftedArray'.
+-- This copies the thawed portion, so mutations will not affect the original
+-- array.
+thawUnliftedArray
+  :: (PrimMonad m)
+  => UnliftedArray a -- ^ source
+  -> Int -- ^ offset
+  -> Int -- ^ length
+  -> m (MutableUnliftedArray (PrimState m) a)
+thawUnliftedArray src off len = do
+  dst <- unsafeNewUnliftedArray len
+  copyUnliftedArray dst 0 src off len
+  return dst
+{-# inline thawUnliftedArray #-}
+
+#if !MIN_VERSION_base(4,9,0)
+unsafeCreateUnliftedArray
+  :: Int
+  -> (forall s. MutableUnliftedArray s a -> ST s ())
+  -> UnliftedArray a
+unsafeCreateUnliftedArray 0 _ = emptyUnliftedArray
+unsafeCreateUnliftedArray n f = runUnliftedArray $ do
+  mary <- unsafeNewUnliftedArray n
+  f mary
+  pure mary
+
+-- | Execute a stateful computation and freeze the resulting array.
+runUnliftedArray
+  :: (forall s. ST s (MutableUnliftedArray s a))
+  -> UnliftedArray a
+runUnliftedArray m = runST $ m >>= unsafeFreezeUnliftedArray
+
+#else /* Below, runRW# is available. */
+
+-- This low-level business is designed to work with GHC's worker-wrapper
+-- transformation. A lot of the time, we don't actually need an Array
+-- constructor. By putting it on the outside, and being careful about
+-- how we special-case the empty array, we can make GHC smarter about this.
+-- The only downside is that separately created 0-length arrays won't share
+-- their Array constructors, although they'll share their underlying
+-- Array#s.
+unsafeCreateUnliftedArray
+  :: Int
+  -> (forall s. MutableUnliftedArray s a -> ST s ())
+  -> UnliftedArray a
+unsafeCreateUnliftedArray 0 _ = UnliftedArray (emptyArrayArray# (# #))
+unsafeCreateUnliftedArray n f = runUnliftedArray $ do
+  mary <- unsafeNewUnliftedArray n
+  f mary
+  pure mary
+
+-- | Execute a stateful computation and freeze the resulting array.
+runUnliftedArray
+  :: (forall s. ST s (MutableUnliftedArray s a))
+  -> UnliftedArray a
+runUnliftedArray m = UnliftedArray (runUnliftedArray# m)
+
+runUnliftedArray#
+  :: (forall s. ST s (MutableUnliftedArray s a))
+  -> ArrayArray#
+runUnliftedArray# m = case runRW# $ \s ->
+  case unST m s of { (# s', MutableUnliftedArray mary# #) ->
+  unsafeFreezeArrayArray# mary# s'} of (# _, ary# #) -> ary#
+
+unST :: ST s a -> State# s -> (# State# s, a #)
+unST (GHCST.ST f) = f
+
+emptyArrayArray# :: (# #) -> ArrayArray#
+emptyArrayArray# _ = case emptyUnliftedArray of UnliftedArray ar -> ar
+{-# NOINLINE emptyArrayArray# #-}
+#endif
+
+-- | Creates a copy of a portion of an 'UnliftedArray'
+cloneUnliftedArray
+  :: UnliftedArray a -- ^ source
+  -> Int -- ^ offset
+  -> Int -- ^ length
+  -> UnliftedArray a
+cloneUnliftedArray src off len =
+  runUnliftedArray (thawUnliftedArray src off len)
+{-# inline cloneUnliftedArray #-}
+
+-- | Creates a new 'MutableUnliftedArray' containing a copy of a portion of
+-- another mutable array.
+cloneMutableUnliftedArray
+  :: (PrimMonad m)
+  => MutableUnliftedArray (PrimState m) a -- ^ source
+  -> Int -- ^ offset
+  -> Int -- ^ length
+  -> m (MutableUnliftedArray (PrimState m) a)
+cloneMutableUnliftedArray src off len = do
+  dst <- unsafeNewUnliftedArray len
+  copyMutableUnliftedArray dst 0 src off len
+  return dst
+{-# inline cloneMutableUnliftedArray #-}
+
+instance Eq (MutableUnliftedArray s a) where
+  (==) = sameMutableUnliftedArray
+
+instance (Eq a, PrimUnlifted a) => Eq (UnliftedArray a) where
+  aa1 == aa2 = sizeofUnliftedArray aa1 == sizeofUnliftedArray aa2
+            && loop (sizeofUnliftedArray aa1 - 1)
+   where
+   loop i
+     | i < 0 = True
+     | otherwise = indexUnliftedArray aa1 i == indexUnliftedArray aa2 i && loop (i-1)
+
+-- | Lexicographic ordering. Subject to change between major versions.
+--
+--   @since 0.6.4.0
+instance (Ord a, PrimUnlifted a) => Ord (UnliftedArray a) where
+  compare a1 a2 = loop 0
+    where
+    mn = sizeofUnliftedArray a1 `min` sizeofUnliftedArray a2
+    loop i
+      | i < mn
+      , x1 <- indexUnliftedArray a1 i
+      , x2 <- indexUnliftedArray a2 i
+      = compare x1 x2 `mappend` loop (i+1)
+      | otherwise = compare (sizeofUnliftedArray a1) (sizeofUnliftedArray a2)
+
+-- | @since 0.6.4.0
+instance (Show a, PrimUnlifted a) => Show (UnliftedArray a) where
+  showsPrec p a = showParen (p > 10) $
+    showString "fromListN " . shows (sizeofUnliftedArray a) . showString " "
+      . shows (unliftedArrayToList a)
+
+#if MIN_VERSION_base(4,9,0)
+-- | @since 0.6.4.0
+instance PrimUnlifted a => Semigroup (UnliftedArray a) where
+  (<>) = concatUnliftedArray
+#endif
+
+-- | @since 0.6.4.0
+instance PrimUnlifted a => Monoid (UnliftedArray a) where
+  mempty = emptyUnliftedArray
+#if !(MIN_VERSION_base(4,11,0))
+  mappend = concatUnliftedArray
+#endif
+
+emptyUnliftedArray :: UnliftedArray a
+emptyUnliftedArray = runUnliftedArray (unsafeNewUnliftedArray 0)
+{-# NOINLINE emptyUnliftedArray #-}
+
+concatUnliftedArray :: UnliftedArray a -> UnliftedArray a -> UnliftedArray a
+concatUnliftedArray x y = unsafeCreateUnliftedArray (sizeofUnliftedArray x + sizeofUnliftedArray y) $ \m -> do
+  copyUnliftedArray m 0 x 0 (sizeofUnliftedArray x)
+  copyUnliftedArray m (sizeofUnliftedArray x) y 0 (sizeofUnliftedArray y)
+
+-- | Lazy right-associated fold over the elements of an 'UnliftedArray'.
+{-# INLINE foldrUnliftedArray #-}
+foldrUnliftedArray :: forall a b. PrimUnlifted a => (a -> b -> b) -> b -> UnliftedArray a -> b
+foldrUnliftedArray f z arr = go 0
+  where
+    !sz = sizeofUnliftedArray arr
+    go !i
+      | sz > i = f (indexUnliftedArray arr i) (go (i+1))
+      | otherwise = z
+
+-- | Strict right-associated fold over the elements of an 'UnliftedArray.
+{-# INLINE foldrUnliftedArray' #-}
+foldrUnliftedArray' :: forall a b. PrimUnlifted a => (a -> b -> b) -> b -> UnliftedArray a -> b
+foldrUnliftedArray' f z0 arr = go (sizeofUnliftedArray arr - 1) z0
+  where
+    go !i !acc
+      | i < 0 = acc
+      | otherwise = go (i - 1) (f (indexUnliftedArray arr i) acc)
+
+-- | Lazy left-associated fold over the elements of an 'UnliftedArray'.
+{-# INLINE foldlUnliftedArray #-}
+foldlUnliftedArray :: forall a b. PrimUnlifted a => (b -> a -> b) -> b -> UnliftedArray a -> b
+foldlUnliftedArray f z arr = go (sizeofUnliftedArray arr - 1)
+  where
+    go !i
+      | i < 0 = z
+      | otherwise = f (go (i - 1)) (indexUnliftedArray arr i)
+
+-- | Strict left-associated fold over the elements of an 'UnliftedArray'.
+{-# INLINE foldlUnliftedArray' #-}
+foldlUnliftedArray' :: forall a b. PrimUnlifted a => (b -> a -> b) -> b -> UnliftedArray a -> b
+foldlUnliftedArray' f z0 arr = go 0 z0
+  where
+    !sz = sizeofUnliftedArray arr
+    go !i !acc
+      | i < sz = go (i + 1) (f acc (indexUnliftedArray arr i))
+      | otherwise = acc
+
+-- | Map over the elements of an 'UnliftedArray'.
+{-# INLINE mapUnliftedArray #-}
+mapUnliftedArray :: (PrimUnlifted a, PrimUnlifted b)
+  => (a -> b)
+  -> UnliftedArray a
+  -> UnliftedArray b
+mapUnliftedArray f arr = unsafeCreateUnliftedArray sz $ \marr -> do
+  let go !ix = if ix < sz
+        then do
+          let b = f (indexUnliftedArray arr ix)
+          writeUnliftedArray marr ix b
+          go (ix + 1)
+        else return ()
+  go 0
+  where
+  !sz = sizeofUnliftedArray arr
+
+-- | Convert the unlifted array to a list.
+{-# INLINE unliftedArrayToList #-}
+unliftedArrayToList :: PrimUnlifted a => UnliftedArray a -> [a]
+unliftedArrayToList xs = build (\c n -> foldrUnliftedArray c n xs)
+
+unliftedArrayFromList :: PrimUnlifted a => [a] -> UnliftedArray a
+unliftedArrayFromList xs = unliftedArrayFromListN (L.length xs) xs
+
+unliftedArrayFromListN :: forall a. PrimUnlifted a => Int -> [a] -> UnliftedArray a
+unliftedArrayFromListN len vs = unsafeCreateUnliftedArray len run where
+  run :: forall s. MutableUnliftedArray s a -> ST s ()
+  run arr = do
+    let go :: [a] -> Int -> ST s ()
+        go [] !ix = if ix == len
+          -- The size check is mandatory since failure to initialize all elements
+          -- introduces the possibility of a segfault happening when someone attempts
+          -- to read the unitialized element. See the docs for unsafeNewUnliftedArray.
+          then return ()
+          else die "unliftedArrayFromListN" "list length less than specified size"
+        go (a : as) !ix = if ix < len
+          then do
+            writeUnliftedArray arr ix a
+            go as (ix + 1)
+          else die "unliftedArrayFromListN" "list length greater than specified size"
+    go vs 0
+
+
+#if MIN_VERSION_base(4,7,0)
+-- | @since 0.6.4.0
+instance PrimUnlifted a => E.IsList (UnliftedArray a) where
+  type Item (UnliftedArray a) = a
+  fromList = unliftedArrayFromList
+  fromListN = unliftedArrayFromListN
+  toList = unliftedArrayToList
+#endif
+

third_party/bazel/rules_haskell/examples/primitive/LICENSE

@@ -0,0 +1,30 @@
+Copyright (c) 2008-2009, Roman Leshchinskiy
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+- Redistributions of source code must retain the above copyright notice,
+this list of conditions and the following disclaimer.
+ 
+- Redistributions in binary form must reproduce the above copyright notice,
+this list of conditions and the following disclaimer in the documentation
+and/or other materials provided with the distribution.
+ 
+- Neither name of the University nor the names of its contributors may be
+used to endorse or promote products derived from this software without
+specific prior written permission. 
+
+THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY COURT OF THE UNIVERSITY OF
+GLASGOW AND THE CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
+INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+UNIVERSITY COURT OF THE UNIVERSITY OF GLASGOW OR THE CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
+DAMAGE.
+

third_party/bazel/rules_haskell/examples/primitive/Setup.hs

@@ -0,0 +1,3 @@
+import Distribution.Simple
+main = defaultMain
+

third_party/bazel/rules_haskell/examples/primitive/cbits/primitive-memops.c

@@ -0,0 +1,56 @@
+#include <string.h>
+#include "primitive-memops.h"
+
+void hsprimitive_memcpy( void *dst, ptrdiff_t doff, void *src, ptrdiff_t soff, size_t len )
+{
+  memcpy( (char *)dst + doff, (char *)src + soff, len );
+}
+
+void hsprimitive_memmove( void *dst, ptrdiff_t doff, void *src, ptrdiff_t soff, size_t len )
+{
+  memmove( (char *)dst + doff, (char *)src + soff, len );
+}
+
+#define MEMSET(TYPE, ATYPE)                                                  \
+void hsprimitive_memset_ ## TYPE (Hs ## TYPE *p, ptrdiff_t off, size_t n, ATYPE x) \
+{                                                                            \
+  p += off;                                                                  \
+  if (x == 0)                                                                \
+    memset(p, 0, n * sizeof(Hs ## TYPE));                                    \
+  else if (sizeof(Hs ## TYPE) == sizeof(int)*2) {                            \
+    int *q = (int *)p;                                                       \
+    const int *r = (const int *)(void *)&x;                                  \
+    while (n>0) {                                                            \
+      q[0] = r[0];                                                           \
+      q[1] = r[1];                                                           \
+      q += 2;                                                                \
+      --n;                                                                   \
+    }                                                                        \
+  }                                                                          \
+  else {                                                                     \
+    while (n>0) {                                                            \
+      *p++ = x;                                                              \
+      --n;                                                                   \
+    }                                                                        \
+  }                                                                          \
+}
+
+int hsprimitive_memcmp( HsWord8 *s1, HsWord8 *s2, size_t n )
+{
+  return memcmp( s1, s2, n );
+}
+
+void hsprimitive_memset_Word8 (HsWord8 *p, ptrdiff_t off, size_t n, HsWord x)
+{
+  memset( (char *)(p+off), x, n );
+}
+
+/* MEMSET(HsWord8, HsWord) */
+MEMSET(Word16, HsWord)
+MEMSET(Word32, HsWord)
+MEMSET(Word64, HsWord64)
+MEMSET(Word, HsWord)
+MEMSET(Ptr, HsPtr)
+MEMSET(Float, HsFloat)
+MEMSET(Double, HsDouble)
+MEMSET(Char, HsChar)

third_party/bazel/rules_haskell/examples/primitive/cbits/primitive-memops.h

@@ -0,0 +1,23 @@
+#ifndef haskell_primitive_memops_h
+#define haskell_primitive_memops_h
+
+#include <stdlib.h>
+#include <stddef.h>
+#include <HsFFI.h>
+
+void hsprimitive_memcpy( void *dst, ptrdiff_t doff, void *src, ptrdiff_t soff, size_t len );
+void hsprimitive_memmove( void *dst, ptrdiff_t doff, void *src, ptrdiff_t soff, size_t len );
+int  hsprimitive_memcmp( HsWord8 *s1, HsWord8 *s2, size_t n );
+
+void hsprimitive_memset_Word8 (HsWord8 *, ptrdiff_t, size_t, HsWord);
+void hsprimitive_memset_Word16 (HsWord16 *, ptrdiff_t, size_t, HsWord);
+void hsprimitive_memset_Word32 (HsWord32 *, ptrdiff_t, size_t, HsWord);
+void hsprimitive_memset_Word64 (HsWord64 *, ptrdiff_t, size_t, HsWord64);
+void hsprimitive_memset_Word (HsWord *, ptrdiff_t, size_t, HsWord);
+void hsprimitive_memset_Ptr (HsPtr *, ptrdiff_t, size_t, HsPtr);
+void hsprimitive_memset_Float (HsFloat *, ptrdiff_t, size_t, HsFloat);
+void hsprimitive_memset_Double (HsDouble *, ptrdiff_t, size_t, HsDouble);
+void hsprimitive_memset_Char (HsChar *, ptrdiff_t, size_t, HsChar);
+
+#endif
+

third_party/bazel/rules_haskell/examples/primitive/changelog.md

@@ -0,0 +1,164 @@
+## Changes in version 0.6.4.0
+
+ * Introduce `Data.Primitive.PrimArray`, which offers types and function
+   for dealing with a `ByteArray` tagged with a phantom type variable for
+   tracking the element type.
+
+ * Implement `isByteArrayPinned` and `isMutableByteArrayPinned`.
+
+ * Add `Eq1`, `Ord1`, `Show1`, and `Read1` instances for `Array` and
+   `SmallArray`.
+
+ * Improve the test suite. This includes having property tests for
+   typeclasses from `base` such as `Eq`, `Ord`, `Functor`, `Applicative`,
+   `Monad`, `IsList`, `Monoid`, `Foldable`, and `Traversable`.
+
+ * Fix the broken `IsList` instance for `ByteArray`. The old definition
+   would allocate a byte array of the correct size and then leave the
+   memory unitialized instead of writing the list elements to it.
+
+ * Fix the broken `Functor` instance for `Array`. The old definition
+   would allocate an array of the correct size with thunks for erroring
+   installed at every index. It failed to replace these thunks with
+   the result of the function applied to the elements of the argument array.
+
+ * Fix the broken `Applicative` instances of `Array` and `SmallArray`.
+   The old implementation of `<*>` for `Array` failed to initialize
+   some elements but correctly initialized others in the resulting
+   `Array`. It is unclear what the old behavior of `<*>` was for
+   `SmallArray`, but it was incorrect.
+
+ * Fix the broken `Monad` instances for `Array` and `SmallArray`.
+
+ * Fix the implementation of `foldl1` in the `Foldable` instances for
+   `Array` and `SmallArray`. In both cases, the old implementation
+   simply returned the first element of the array and made no use of
+   the other elements in the array.
+
+ * Fix the implementation of `mconcat` in the `Monoid` instance for
+   `SmallArray`.
+ 
+ * Implement `Data.Primitive.Ptr`, implementations of `Ptr` functions
+   that require a `Prim` constraint instead of a `Storable` constraint.
+
+
+ * Add `PrimUnlifted` instances for `TVar` and `MVar`.
+
+ * Use `compareByteArrays#` for the `Eq` and `Ord` instances of
+   `ByteArray` when building with GHC 8.4 and newer.
+
+ * Add `Prim` instances for lots of types in `Foreign.C.Types` and
+   `System.Posix.Types`.
+
+ * Reexport `Data.Primitive.SmallArray` and `Data.Primitive.UnliftedArray`
+   from `Data.Primitive`.
+
+ * Add fold functions and map function to `Data.Primitive.UnliftedArray`.
+   Add typeclass instances for `IsList`, `Ord`, and `Show`.
+
+ * Add `defaultSetByteArray#` and `defaultSetOffAddr#` to
+   `Data.Primitive.Types`.
+
+## Changes in version 0.6.3.0
+
+ * Add `PrimMonad` instances for `ContT`, `AccumT`, and `SelectT` from
+   `transformers`
+
+ * Add `Eq`, `Ord`, `Show`, and `IsList` instances for `ByteArray`
+
+ * Add `Semigroup` instances for `Array` and `SmallArray`. This allows
+   `primitive` to build on GHC 8.4 and later.
+
+## Changes in version 0.6.2.0
+
+ * Drop support for GHCs before 7.4
+
+ * `SmallArray` support
+
+ * `ArrayArray#` based support for more efficient arrays of unlifted pointer types
+
+ * Make `Array` and the like instances of various classes for convenient use
+
+ * Add `Prim` instances for Ptr and FunPtr
+
+ * Add `ioToPrim`, `stToPrim` and unsafe counterparts for situations that would
+   otherwise require type ascriptions on `primToPrim`
+
+ * Add `evalPrim`
+
+ * Add `PrimBase` instance for `IdentityT`
+
+## Changes in version 0.6.1.0
+
+ * Use more appropriate types in internal memset functions, which prevents
+   overflows/segfaults on 64-bit systems.
+
+ * Fixed a warning on GHC 7.10
+
+ * Worked around a -dcore-lint bug in GHC 7.6/7.7
+
+## Changes in version 0.6
+
+ * Split PrimMonad into two classes to allow automatic lifting of primitive
+   operations into monad transformers. The `internal` operation has moved to the
+   `PrimBase` class.
+
+ * Fixed the test suite on older GHCs
+
+## Changes in version 0.5.4.0
+
+ * Changed primitive_ to work around an oddity with GHC's code generation
+   on certain versions that led to side effects not happening when used
+   in conjunction with certain very unsafe IO performers.
+
+ * Allow primitive to build on GHC 7.9
+
+## Changes in version 0.5.3.0
+
+ * Implement `cloneArray` and `cloneMutableArray` primitives
+   (with fall-back implementations for GHCs prior to version 7.2.1)
+
+## Changes in version 0.5.2.1
+
+ * Add strict variants of `MutVar` modification functions
+   `atomicModifyMutVar'` and `modifyMutVar'`
+
+ * Fix compilation on Solaris 10 with GNU C 3.4.3
+
+## Changes in version 0.5.1.0
+
+ * Add support for GHC 7.7's new primitive `Bool` representation
+
+## Changes in version 0.5.0.1
+
+ * Disable array copying primitives for GHC 7.6.* and earlier
+
+## Changes in version 0.5
+
+ * New in `Data.Primitive.MutVar`: `atomicModifyMutVar`
+
+ * Efficient block fill operations: `setByteArray`, `setAddr`
+
+## Changes in version 0.4.1
+
+ * New module `Data.Primitive.MutVar`
+
+## Changes in version 0.4.0.1
+
+ * Critical bug fix in `fillByteArray`
+
+## Changes in version 0.4
+
+ * Support for GHC 7.2 array copying primitives
+
+ * New in `Data.Primitive.ByteArray`: `copyByteArray`,
+   `copyMutableByteArray`, `moveByteArray`, `fillByteArray`
+
+ * Deprecated in `Data.Primitive.ByteArray`: `memcpyByteArray`,
+   `memcpyByteArray'`, `memmoveByteArray`, `memsetByteArray`
+
+ * New in `Data.Primitive.Array`: `copyArray`, `copyMutableByteArray`
+
+ * New in `Data.Primitive.Addr`: `copyAddr`, `moveAddr`
+
+ * Deprecated in `Data.Primitive.Addr`: `memcpyAddr`

third_party/bazel/rules_haskell/examples/primitive/primitive.cabal

@@ -0,0 +1,74 @@
+Name:           primitive
+Version:        0.6.4.0
+x-revision: 1
+License:        BSD3
+License-File:   LICENSE
+
+Author:         Roman Leshchinskiy <rl@cse.unsw.edu.au>
+Maintainer:     libraries@haskell.org
+Copyright:      (c) Roman Leshchinskiy 2009-2012
+Homepage:       https://github.com/haskell/primitive
+Bug-Reports:    https://github.com/haskell/primitive/issues
+Category:       Data
+Synopsis:       Primitive memory-related operations
+Cabal-Version:  >= 1.10
+Build-Type:     Simple
+Description:    This package provides various primitive memory-related operations.
+
+Extra-Source-Files: changelog.md
+                    test/*.hs
+                    test/LICENSE
+                    test/primitive-tests.cabal
+
+Tested-With:
+  GHC == 7.4.2,
+  GHC == 7.6.3,
+  GHC == 7.8.4,
+  GHC == 7.10.3,
+  GHC == 8.0.2,
+  GHC == 8.2.2,
+  GHC == 8.4.2
+
+Library
+  Default-Language: Haskell2010
+  Other-Extensions:
+        BangPatterns, CPP, DeriveDataTypeable,
+        MagicHash, TypeFamilies, UnboxedTuples, UnliftedFFITypes
+
+  Exposed-Modules:
+        Control.Monad.Primitive
+        Data.Primitive
+        Data.Primitive.MachDeps
+        Data.Primitive.Types
+        Data.Primitive.Array
+        Data.Primitive.ByteArray
+        Data.Primitive.PrimArray
+        Data.Primitive.SmallArray
+        Data.Primitive.UnliftedArray
+        Data.Primitive.Addr
+        Data.Primitive.Ptr
+        Data.Primitive.MutVar
+        Data.Primitive.MVar
+
+  Other-Modules:
+        Data.Primitive.Internal.Compat
+        Data.Primitive.Internal.Operations
+
+  Build-Depends: base >= 4.5 && < 4.13
+               , ghc-prim >= 0.2 && < 0.6
+               , transformers >= 0.2 && < 0.6
+
+  Ghc-Options: -O2
+
+  Include-Dirs: cbits
+  Install-Includes: primitive-memops.h
+  includes: primitive-memops.h
+  c-sources: cbits/primitive-memops.c
+  if !os(solaris)
+      cc-options: -ftree-vectorize
+  if arch(i386) || arch(x86_64)
+      cc-options: -msse2
+
+source-repository head
+  type:     git
+  location: https://github.com/haskell/primitive

third_party/bazel/rules_haskell/examples/primitive/test/LICENSE

@@ -0,0 +1,30 @@
+Copyright (c) 2008-2009, Roman Leshchinskiy
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+- Redistributions of source code must retain the above copyright notice,
+this list of conditions and the following disclaimer.
+ 
+- Redistributions in binary form must reproduce the above copyright notice,
+this list of conditions and the following disclaimer in the documentation
+and/or other materials provided with the distribution.
+ 
+- Neither name of the University nor the names of its contributors may be
+used to endorse or promote products derived from this software without
+specific prior written permission. 
+
+THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY COURT OF THE UNIVERSITY OF
+GLASGOW AND THE CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
+INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+UNIVERSITY COURT OF THE UNIVERSITY OF GLASGOW OR THE CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
+DAMAGE.
+

third_party/bazel/rules_haskell/examples/primitive/test/main.hs

@@ -0,0 +1,342 @@
+{-# LANGUAGE BangPatterns #-}
+{-# LANGUAGE CPP #-}
+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
+{-# LANGUAGE KindSignatures #-}
+{-# LANGUAGE MagicHash #-}
+{-# LANGUAGE UnboxedTuples #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+
+import Control.Applicative
+import Control.Monad
+import Control.Monad.Fix (fix)
+import Control.Monad.Primitive
+import Control.Monad.ST
+import Data.Monoid
+import Data.Primitive
+import Data.Primitive.Array
+import Data.Primitive.ByteArray
+import Data.Primitive.Types
+import Data.Primitive.SmallArray
+import Data.Primitive.PrimArray
+import Data.Word
+import Data.Proxy (Proxy(..))
+import GHC.Int
+import GHC.IO
+import GHC.Prim
+import Data.Function (on)
+#if MIN_VERSION_base(4,9,0)
+import Data.Semigroup (stimes)
+#endif
+
+import Test.Tasty (defaultMain,testGroup,TestTree)
+import Test.QuickCheck (Arbitrary,Arbitrary1,Gen,(===),CoArbitrary,Function)
+import qualified Test.Tasty.QuickCheck as TQC
+import qualified Test.QuickCheck as QC
+import qualified Test.QuickCheck.Classes as QCC
+import qualified Test.QuickCheck.Classes.IsList as QCCL
+import qualified Data.List as L
+
+main :: IO ()
+main = do
+  testArray
+  testByteArray
+  defaultMain $ testGroup "properties"
+    [ testGroup "Array"
+      [ lawsToTest (QCC.eqLaws (Proxy :: Proxy (Array Int)))
+      , lawsToTest (QCC.ordLaws (Proxy :: Proxy (Array Int)))
+      , lawsToTest (QCC.monoidLaws (Proxy :: Proxy (Array Int)))
+      , lawsToTest (QCC.showReadLaws (Proxy :: Proxy (Array Int)))
+#if MIN_VERSION_base(4,9,0) || MIN_VERSION_transformers(0,4,0)
+      , lawsToTest (QCC.functorLaws (Proxy1 :: Proxy1 Array))
+      , lawsToTest (QCC.applicativeLaws (Proxy1 :: Proxy1 Array))
+      , lawsToTest (QCC.monadLaws (Proxy1 :: Proxy1 Array))
+      , lawsToTest (QCC.foldableLaws (Proxy1 :: Proxy1 Array))
+      , lawsToTest (QCC.traversableLaws (Proxy1 :: Proxy1 Array))
+#endif
+#if MIN_VERSION_base(4,7,0)
+      , lawsToTest (QCC.isListLaws (Proxy :: Proxy (Array Int)))
+      , TQC.testProperty "mapArray'" (QCCL.mapProp int16 int32 mapArray')
+#endif
+      ]
+    , testGroup "SmallArray"
+      [ lawsToTest (QCC.eqLaws (Proxy :: Proxy (SmallArray Int)))
+      , lawsToTest (QCC.ordLaws (Proxy :: Proxy (SmallArray Int)))
+      , lawsToTest (QCC.monoidLaws (Proxy :: Proxy (SmallArray Int)))
+      , lawsToTest (QCC.showReadLaws (Proxy :: Proxy (Array Int)))
+#if MIN_VERSION_base(4,9,0) || MIN_VERSION_transformers(0,4,0)
+      , lawsToTest (QCC.functorLaws (Proxy1 :: Proxy1 SmallArray))
+      , lawsToTest (QCC.applicativeLaws (Proxy1 :: Proxy1 SmallArray))
+      , lawsToTest (QCC.monadLaws (Proxy1 :: Proxy1 SmallArray))
+      , lawsToTest (QCC.foldableLaws (Proxy1 :: Proxy1 SmallArray))
+      , lawsToTest (QCC.traversableLaws (Proxy1 :: Proxy1 SmallArray))
+#endif
+#if MIN_VERSION_base(4,7,0)
+      , lawsToTest (QCC.isListLaws (Proxy :: Proxy (SmallArray Int)))
+      , TQC.testProperty "mapSmallArray'" (QCCL.mapProp int16 int32 mapSmallArray')
+#endif
+      ]
+    , testGroup "ByteArray"
+      [ testGroup "Ordering"
+        [ TQC.testProperty "equality" byteArrayEqProp
+        , TQC.testProperty "compare" byteArrayCompareProp
+        ]
+      , testGroup "Resize"
+        [ TQC.testProperty "shrink" byteArrayShrinkProp
+        , TQC.testProperty "grow" byteArrayGrowProp
+        ]
+      , lawsToTest (QCC.eqLaws (Proxy :: Proxy ByteArray))
+      , lawsToTest (QCC.ordLaws (Proxy :: Proxy ByteArray))
+      , lawsToTest (QCC.showReadLaws (Proxy :: Proxy (Array Int)))
+#if MIN_VERSION_base(4,7,0)
+      , lawsToTest (QCC.isListLaws (Proxy :: Proxy ByteArray))
+#endif
+      ]
+    , testGroup "PrimArray"
+      [ lawsToTest (QCC.eqLaws (Proxy :: Proxy (PrimArray Word16)))
+      , lawsToTest (QCC.ordLaws (Proxy :: Proxy (PrimArray Word16)))
+      , lawsToTest (QCC.monoidLaws (Proxy :: Proxy (PrimArray Word16)))
+#if MIN_VERSION_base(4,7,0)
+      , lawsToTest (QCC.isListLaws (Proxy :: Proxy (PrimArray Word16)))
+      , TQC.testProperty "foldrPrimArray" (QCCL.foldrProp int16 foldrPrimArray)
+      , TQC.testProperty "foldrPrimArray'" (QCCL.foldrProp int16 foldrPrimArray')
+      , TQC.testProperty "foldlPrimArray" (QCCL.foldlProp int16 foldlPrimArray)
+      , TQC.testProperty "foldlPrimArray'" (QCCL.foldlProp int16 foldlPrimArray')
+      , TQC.testProperty "foldlPrimArrayM'" (QCCL.foldlMProp int16 foldlPrimArrayM')
+      , TQC.testProperty "mapPrimArray" (QCCL.mapProp int16 int32 mapPrimArray)
+      , TQC.testProperty "traversePrimArray" (QCCL.traverseProp int16 int32 traversePrimArray)
+      , TQC.testProperty "traversePrimArrayP" (QCCL.traverseProp int16 int32 traversePrimArrayP)
+      , TQC.testProperty "imapPrimArray" (QCCL.imapProp int16 int32 imapPrimArray)
+      , TQC.testProperty "itraversePrimArray" (QCCL.imapMProp int16 int32 itraversePrimArray)
+      , TQC.testProperty "itraversePrimArrayP" (QCCL.imapMProp int16 int32 itraversePrimArrayP)
+      , TQC.testProperty "generatePrimArray" (QCCL.generateProp int16 generatePrimArray)
+      , TQC.testProperty "generatePrimArrayA" (QCCL.generateMProp int16 generatePrimArrayA)
+      , TQC.testProperty "generatePrimArrayP" (QCCL.generateMProp int16 generatePrimArrayP)
+      , TQC.testProperty "replicatePrimArray" (QCCL.replicateProp int16 replicatePrimArray)
+      , TQC.testProperty "replicatePrimArrayA" (QCCL.replicateMProp int16 replicatePrimArrayA)
+      , TQC.testProperty "replicatePrimArrayP" (QCCL.replicateMProp int16 replicatePrimArrayP)
+      , TQC.testProperty "filterPrimArray" (QCCL.filterProp int16 filterPrimArray)
+      , TQC.testProperty "filterPrimArrayA" (QCCL.filterMProp int16 filterPrimArrayA)
+      , TQC.testProperty "filterPrimArrayP" (QCCL.filterMProp int16 filterPrimArrayP)
+      , TQC.testProperty "mapMaybePrimArray" (QCCL.mapMaybeProp int16 int32 mapMaybePrimArray)
+      , TQC.testProperty "mapMaybePrimArrayA" (QCCL.mapMaybeMProp int16 int32 mapMaybePrimArrayA)
+      , TQC.testProperty "mapMaybePrimArrayP" (QCCL.mapMaybeMProp int16 int32 mapMaybePrimArrayP)
+#endif
+      ]
+    , testGroup "UnliftedArray"
+      [ lawsToTest (QCC.eqLaws (Proxy :: Proxy (UnliftedArray (PrimArray Int16))))
+      , lawsToTest (QCC.ordLaws (Proxy :: Proxy (UnliftedArray (PrimArray Int16))))
+      , lawsToTest (QCC.monoidLaws (Proxy :: Proxy (UnliftedArray (PrimArray Int16))))
+#if MIN_VERSION_base(4,7,0)
+      , lawsToTest (QCC.isListLaws (Proxy :: Proxy (UnliftedArray (PrimArray Int16))))
+      , TQC.testProperty "mapUnliftedArray" (QCCL.mapProp arrInt16 arrInt32 mapUnliftedArray)
+      , TQC.testProperty "foldrUnliftedArray" (QCCL.foldrProp arrInt16 foldrUnliftedArray)
+      , TQC.testProperty "foldrUnliftedArray'" (QCCL.foldrProp arrInt16 foldrUnliftedArray')
+      , TQC.testProperty "foldlUnliftedArray" (QCCL.foldlProp arrInt16 foldlUnliftedArray)
+      , TQC.testProperty "foldlUnliftedArray'" (QCCL.foldlProp arrInt16 foldlUnliftedArray')
+#endif
+      ]
+    , testGroup "DefaultSetMethod"
+      [ lawsToTest (QCC.primLaws (Proxy :: Proxy DefaultSetMethod))
+      ]
+    -- , testGroup "PrimStorable"
+    --   [ lawsToTest (QCC.storableLaws (Proxy :: Proxy Derived))
+    --   ]
+    ]
+
+int16 :: Proxy Int16
+int16 = Proxy
+
+int32 :: Proxy Int32
+int32 = Proxy
+
+arrInt16 :: Proxy (PrimArray Int16)
+arrInt16 = Proxy
+
+arrInt32 :: Proxy (PrimArray Int16)
+arrInt32 = Proxy
+
+-- Tests that using resizeByteArray to shrink a byte array produces
+-- the same results as calling Data.List.take on the list that the
+-- byte array corresponds to.
+byteArrayShrinkProp :: QC.Property
+byteArrayShrinkProp = QC.property $ \(QC.NonNegative (n :: Int)) (QC.NonNegative (m :: Int)) ->
+  let large = max n m
+      small = min n m
+      xs = intsLessThan large
+      ys = byteArrayFromList xs
+      largeBytes = large * sizeOf (undefined :: Int)
+      smallBytes = small * sizeOf (undefined :: Int)
+      expected = byteArrayFromList (L.take small xs)
+      actual = runST $ do
+        mzs0 <- newByteArray largeBytes
+        copyByteArray mzs0 0 ys 0 largeBytes
+        mzs1 <- resizeMutableByteArray mzs0 smallBytes
+        unsafeFreezeByteArray mzs1
+   in expected === actual
+
+-- Tests that using resizeByteArray with copyByteArray (to fill in the
+-- new empty space) to grow a byte array produces the same results as
+-- calling Data.List.++ on the lists corresponding to the original
+-- byte array and the appended byte array.
+byteArrayGrowProp :: QC.Property
+byteArrayGrowProp = QC.property $ \(QC.NonNegative (n :: Int)) (QC.NonNegative (m :: Int)) ->
+  let large = max n m
+      small = min n m
+      xs1 = intsLessThan small
+      xs2 = intsLessThan (large - small)
+      ys1 = byteArrayFromList xs1
+      ys2 = byteArrayFromList xs2
+      largeBytes = large * sizeOf (undefined :: Int)
+      smallBytes = small * sizeOf (undefined :: Int)
+      expected = byteArrayFromList (xs1 ++ xs2)
+      actual = runST $ do
+        mzs0 <- newByteArray smallBytes
+        copyByteArray mzs0 0 ys1 0 smallBytes
+        mzs1 <- resizeMutableByteArray mzs0 largeBytes
+        copyByteArray mzs1 smallBytes ys2 0 ((large - small) * sizeOf (undefined :: Int))
+        unsafeFreezeByteArray mzs1
+   in expected === actual
+
+-- Provide the non-negative integers up to the bound. For example:
+--
+-- >>> intsLessThan 5
+-- [0,1,2,3,4]
+intsLessThan :: Int -> [Int]
+intsLessThan i = if i < 1
+  then []
+  else (i - 1) : intsLessThan (i - 1)
+  
+byteArrayCompareProp :: QC.Property
+byteArrayCompareProp = QC.property $ \(xs :: [Word8]) (ys :: [Word8]) ->
+  compareLengthFirst xs ys === compare (byteArrayFromList xs) (byteArrayFromList ys)
+
+byteArrayEqProp :: QC.Property
+byteArrayEqProp = QC.property $ \(xs :: [Word8]) (ys :: [Word8]) ->
+  (compareLengthFirst xs ys == EQ) === (byteArrayFromList xs == byteArrayFromList ys)
+
+compareLengthFirst :: [Word8] -> [Word8] -> Ordering
+compareLengthFirst xs ys = (compare `on` length) xs ys <> compare xs ys
+
+-- on GHC 7.4, Proxy is not polykinded, so we need this instead.
+data Proxy1 (f :: * -> *) = Proxy1
+
+lawsToTest :: QCC.Laws -> TestTree
+lawsToTest (QCC.Laws name pairs) = testGroup name (map (uncurry TQC.testProperty) pairs)
+
+testArray :: IO ()
+testArray = do
+    arr <- newArray 1 'A'
+    let unit =
+            case writeArray arr 0 'B' of
+                IO f ->
+                    case f realWorld# of
+                        (# _, _ #) -> ()
+    c1 <- readArray arr 0
+    return $! unit
+    c2 <- readArray arr 0
+    if c1 == 'A' && c2 == 'B'
+        then return ()
+        else error $ "Expected AB, got: " ++ show (c1, c2)
+
+testByteArray :: IO ()
+testByteArray = do
+    let arr1 = mkByteArray ([0xde, 0xad, 0xbe, 0xef] :: [Word8])
+        arr2 = mkByteArray ([0xde, 0xad, 0xbe, 0xef] :: [Word8])
+        arr3 = mkByteArray ([0xde, 0xad, 0xbe, 0xee] :: [Word8])
+        arr4 = mkByteArray ([0xde, 0xad, 0xbe, 0xdd] :: [Word8])
+        arr5 = mkByteArray ([0xde, 0xad, 0xbe, 0xef, 0xde, 0xad, 0xbe, 0xdd] :: [Word8])
+    when (show arr1 /= "[0xde, 0xad, 0xbe, 0xef]") $
+        fail $ "ByteArray Show incorrect: "++show arr1
+    unless (arr1 > arr3) $
+        fail $ "ByteArray Ord incorrect"
+    unless (arr1 == arr2) $
+        fail $ "ByteArray Eq incorrect"
+    unless (mappend arr1 arr4 == arr5) $
+        fail $ "ByteArray Monoid mappend incorrect"
+    unless (mappend arr1 (mappend arr3 arr4) == mappend (mappend arr1 arr3) arr4) $
+        fail $ "ByteArray Monoid mappend not associative"
+    unless (mconcat [arr1,arr2,arr3,arr4,arr5] == (arr1 <> arr2 <> arr3 <> arr4 <> arr5)) $
+        fail $ "ByteArray Monoid mconcat incorrect"
+#if MIN_VERSION_base(4,9,0)
+    unless (stimes (3 :: Int) arr4 == (arr4 <> arr4 <> arr4)) $
+        fail $ "ByteArray Semigroup stimes incorrect"
+#endif
+
+mkByteArray :: Prim a => [a] -> ByteArray
+mkByteArray xs = runST $ do
+    marr <- newByteArray (length xs * sizeOf (head xs))
+    sequence $ zipWith (writeByteArray marr) [0..] xs
+    unsafeFreezeByteArray marr
+
+instance Arbitrary1 Array where
+  liftArbitrary elemGen = fmap fromList (QC.liftArbitrary elemGen)
+
+instance Arbitrary a => Arbitrary (Array a) where
+  arbitrary = fmap fromList QC.arbitrary
+
+instance Arbitrary1 SmallArray where
+  liftArbitrary elemGen = fmap smallArrayFromList (QC.liftArbitrary elemGen)
+
+instance Arbitrary a => Arbitrary (SmallArray a) where
+  arbitrary = fmap smallArrayFromList QC.arbitrary
+
+instance Arbitrary ByteArray where
+  arbitrary = do
+    xs <- QC.arbitrary :: Gen [Word8]
+    return $ runST $ do
+      a <- newByteArray (L.length xs)
+      iforM_ xs $ \ix x -> do
+        writeByteArray a ix x
+      unsafeFreezeByteArray a
+
+instance (Arbitrary a, Prim a) => Arbitrary (PrimArray a) where
+  arbitrary = do
+    xs <- QC.arbitrary :: Gen [a]
+    return $ runST $ do
+      a <- newPrimArray (L.length xs)
+      iforM_ xs $ \ix x -> do
+        writePrimArray a ix x
+      unsafeFreezePrimArray a
+
+instance (Arbitrary a, PrimUnlifted a) => Arbitrary (UnliftedArray a) where
+  arbitrary = do
+    xs <- QC.vector =<< QC.choose (0,3)
+    return (unliftedArrayFromList xs)
+
+instance (Prim a, CoArbitrary a) => CoArbitrary (PrimArray a) where
+  coarbitrary x = QC.coarbitrary (primArrayToList x)
+
+instance (Prim a, Function a) => Function (PrimArray a) where
+  function = QC.functionMap primArrayToList primArrayFromList
+
+iforM_ :: Monad m => [a] -> (Int -> a -> m b) -> m ()
+iforM_ xs0 f = go 0 xs0 where
+  go !_ [] = return ()
+  go !ix (x : xs) = f ix x >> go (ix + 1) xs
+
+newtype DefaultSetMethod = DefaultSetMethod Int16
+  deriving (Eq,Show,Arbitrary)
+
+instance Prim DefaultSetMethod where
+  sizeOf# _ = sizeOf# (undefined :: Int16)
+  alignment# _ = alignment# (undefined :: Int16)
+  indexByteArray# arr ix = DefaultSetMethod (indexByteArray# arr ix)
+  readByteArray# arr ix s0 = case readByteArray# arr ix s0 of
+    (# s1, n #) -> (# s1, DefaultSetMethod n #)
+  writeByteArray# arr ix (DefaultSetMethod n) s0 = writeByteArray# arr ix n s0
+  setByteArray# = defaultSetByteArray#
+  indexOffAddr# addr off = DefaultSetMethod (indexOffAddr# addr off)
+  readOffAddr# addr off s0 = case readOffAddr# addr off s0 of
+    (# s1, n #) -> (# s1, DefaultSetMethod n #)
+  writeOffAddr# addr off (DefaultSetMethod n) s0 = writeOffAddr# addr off n s0
+  setOffAddr# = defaultSetOffAddr#
+
+-- TODO: Uncomment this out when GHC 8.6 is release. Also, uncomment
+-- the corresponding PrimStorable test group above.
+--
+-- newtype Derived = Derived Int16
+--   deriving newtype (Prim)
+--   deriving Storable via (PrimStorable Derived)
+
+
+

third_party/bazel/rules_haskell/examples/primitive/test/primitive-tests.cabal

@@ -0,0 +1,45 @@
+Name:           primitive-tests
+Version:        0.1
+License:        BSD3
+License-File:   LICENSE
+
+Author:         Roman Leshchinskiy <rl@cse.unsw.edu.au>
+Maintainer:     libraries@haskell.org
+Copyright:      (c) Roman Leshchinskiy 2009-2012
+Homepage:       https://github.com/haskell/primitive
+Bug-Reports:    https://github.com/haskell/primitive/issues
+Category:       Data
+Synopsis:       primitive tests
+Cabal-Version:  >= 1.10
+Build-Type:     Simple
+Description:    @primitive@ tests
+
+Tested-With:
+  GHC == 7.4.2,
+  GHC == 7.6.3,
+  GHC == 7.8.4,
+  GHC == 7.10.3,
+  GHC == 8.0.2,
+  GHC == 8.2.2,
+  GHC == 8.4.2
+
+test-suite test
+  Default-Language: Haskell2010
+  hs-source-dirs: .
+  main-is: main.hs
+  type: exitcode-stdio-1.0
+  build-depends: base >= 4.5 && < 4.12
+               , ghc-prim
+               , primitive
+               , QuickCheck
+               , tasty
+               , tasty-quickcheck
+               , tagged
+               , transformers >= 0.3
+               , quickcheck-classes >= 0.4.11.1
+  ghc-options: -O2
+
+source-repository head
+  type:     git
+  location: https://github.com/haskell/primitive
+  subdir:   test

third_party/bazel/rules_haskell/examples/rts/BUILD.bazel

@@ -0,0 +1,29 @@
+load(
+    "@io_tweag_rules_haskell//haskell:haskell.bzl",
+    "cc_haskell_import",
+    "haskell_library",
+    "haskell_toolchain_library",
+)
+
+haskell_toolchain_library(name = "base")
+
+haskell_library(
+    name = "add-one-hs",
+    srcs = ["One.hs"],
+    deps = [":base"],
+)
+
+cc_haskell_import(
+    name = "add-one-so",
+    dep = ":add-one-hs",
+)
+
+cc_test(
+    name = "add-one",
+    srcs = [
+        "main.c",
+        ":add-one-so",
+    ],
+    visibility = ["//visibility:public"],
+    deps = ["@ghc//:threaded-rts"],
+)

third_party/bazel/rules_haskell/examples/rts/One.hs

@@ -0,0 +1,6 @@
+module One () where
+
+add_one_hs :: Int -> Int
+add_one_hs x = x + 1
+
+foreign export ccall add_one_hs :: Int -> Int

third_party/bazel/rules_haskell/examples/rts/main.c

@@ -0,0 +1,11 @@
+#include <stdio.h>
+#include "HsFFI.h"
+
+extern HsInt add_one_hs(HsInt a0);
+
+int main(int argc, char *argv[]) {
+  hs_init(&argc, &argv);
+  printf("Adding one to 5 through Haskell is %ld\n", add_one_hs(5));
+  hs_exit();
+  return 0;
+}

third_party/bazel/rules_haskell/examples/transformers/BUILD.bazel

@@ -0,0 +1,19 @@
+load(
+    "@io_tweag_rules_haskell//haskell:haskell.bzl",
+    "haskell_cc_import",
+    "haskell_library",
+    "haskell_toolchain_library",
+)
+
+haskell_toolchain_library(name = "base")
+
+haskell_library(
+    name = "transformers",
+    srcs = glob([
+        "Data/**/*.hs",
+        "Control/**/*.hs",
+    ]),
+    version = "0",
+    visibility = ["//visibility:public"],
+    deps = [":base"],
+)

third_party/bazel/rules_haskell/examples/transformers/Control/Applicative/Backwards.hs

@@ -0,0 +1,112 @@
+{-# LANGUAGE CPP #-}
+#if __GLASGOW_HASKELL__ >= 702
+{-# LANGUAGE Safe #-}
+#endif
+#if __GLASGOW_HASKELL__ >= 706
+{-# LANGUAGE PolyKinds #-}
+#endif
+#if __GLASGOW_HASKELL__ >= 710
+{-# LANGUAGE AutoDeriveTypeable #-}
+#endif
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Control.Applicative.Backwards
+-- Copyright   :  (c) Russell O'Connor 2009
+-- License     :  BSD-style (see the file LICENSE)
+--
+-- Maintainer  :  R.Paterson@city.ac.uk
+-- Stability   :  experimental
+-- Portability :  portable
+--
+-- Making functors with an 'Applicative' instance that performs actions
+-- in the reverse order.
+-----------------------------------------------------------------------------
+
+module Control.Applicative.Backwards (
+    Backwards(..),
+  ) where
+
+import Data.Functor.Classes
+#if MIN_VERSION_base(4,12,0)
+import Data.Functor.Contravariant
+#endif
+
+import Prelude hiding (foldr, foldr1, foldl, foldl1, null, length)
+import Control.Applicative
+import Data.Foldable
+import Data.Traversable
+
+-- | The same functor, but with an 'Applicative' instance that performs
+-- actions in the reverse order.
+newtype Backwards f a = Backwards { forwards :: f a }
+
+instance (Eq1 f) => Eq1 (Backwards f) where
+    liftEq eq (Backwards x) (Backwards y) = liftEq eq x y
+    {-# INLINE liftEq #-}
+
+instance (Ord1 f) => Ord1 (Backwards f) where
+    liftCompare comp (Backwards x) (Backwards y) = liftCompare comp x y
+    {-# INLINE liftCompare #-}
+
+instance (Read1 f) => Read1 (Backwards f) where
+    liftReadsPrec rp rl = readsData $
+        readsUnaryWith (liftReadsPrec rp rl) "Backwards" Backwards
+
+instance (Show1 f) => Show1 (Backwards f) where
+    liftShowsPrec sp sl d (Backwards x) =
+        showsUnaryWith (liftShowsPrec sp sl) "Backwards" d x
+
+instance (Eq1 f, Eq a) => Eq (Backwards f a) where (==) = eq1
+instance (Ord1 f, Ord a) => Ord (Backwards f a) where compare = compare1
+instance (Read1 f, Read a) => Read (Backwards f a) where readsPrec = readsPrec1
+instance (Show1 f, Show a) => Show (Backwards f a) where showsPrec = showsPrec1
+
+-- | Derived instance.
+instance (Functor f) => Functor (Backwards f) where
+    fmap f (Backwards a) = Backwards (fmap f a)
+    {-# INLINE fmap #-}
+
+-- | Apply @f@-actions in the reverse order.
+instance (Applicative f) => Applicative (Backwards f) where
+    pure a = Backwards (pure a)
+    {-# INLINE pure #-}
+    Backwards f <*> Backwards a = Backwards (a <**> f)
+    {-# INLINE (<*>) #-}
+
+-- | Try alternatives in the same order as @f@.
+instance (Alternative f) => Alternative (Backwards f) where
+    empty = Backwards empty
+    {-# INLINE empty #-}
+    Backwards x <|> Backwards y = Backwards (x <|> y)
+    {-# INLINE (<|>) #-}
+
+-- | Derived instance.
+instance (Foldable f) => Foldable (Backwards f) where
+    foldMap f (Backwards t) = foldMap f t
+    {-# INLINE foldMap #-}
+    foldr f z (Backwards t) = foldr f z t
+    {-# INLINE foldr #-}
+    foldl f z (Backwards t) = foldl f z t
+    {-# INLINE foldl #-}
+    foldr1 f (Backwards t) = foldr1 f t
+    {-# INLINE foldr1 #-}
+    foldl1 f (Backwards t) = foldl1 f t
+    {-# INLINE foldl1 #-}
+#if MIN_VERSION_base(4,8,0)
+    null (Backwards t) = null t
+    length (Backwards t) = length t
+#endif
+
+-- | Derived instance.
+instance (Traversable f) => Traversable (Backwards f) where
+    traverse f (Backwards t) = fmap Backwards (traverse f t)
+    {-# INLINE traverse #-}
+    sequenceA (Backwards t) = fmap Backwards (sequenceA t)
+    {-# INLINE sequenceA #-}
+
+#if MIN_VERSION_base(4,12,0)
+-- | Derived instance.
+instance Contravariant f => Contravariant (Backwards f) where
+    contramap f = Backwards . contramap f . forwards
+    {-# INLINE contramap #-}
+#endif

third_party/bazel/rules_haskell/examples/transformers/Control/Applicative/Lift.hs

@@ -0,0 +1,165 @@
+{-# LANGUAGE CPP #-}
+#if __GLASGOW_HASKELL__ >= 702
+{-# LANGUAGE Safe #-}
+#endif
+#if __GLASGOW_HASKELL__ >= 710
+{-# LANGUAGE AutoDeriveTypeable #-}
+#endif
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Control.Applicative.Lift
+-- Copyright   :  (c) Ross Paterson 2010
+-- License     :  BSD-style (see the file LICENSE)
+--
+-- Maintainer  :  R.Paterson@city.ac.uk
+-- Stability   :  experimental
+-- Portability :  portable
+--
+-- Adding a new kind of pure computation to an applicative functor.
+-----------------------------------------------------------------------------
+
+module Control.Applicative.Lift (
+    -- * Lifting an applicative
+    Lift(..),
+    unLift,
+    mapLift,
+    elimLift,
+    -- * Collecting errors
+    Errors,
+    runErrors,
+    failure,
+    eitherToErrors
+  ) where
+
+import Data.Functor.Classes
+
+import Control.Applicative
+import Data.Foldable (Foldable(foldMap))
+import Data.Functor.Constant
+import Data.Monoid (Monoid(..))
+import Data.Traversable (Traversable(traverse))
+
+-- | Applicative functor formed by adding pure computations to a given
+-- applicative functor.
+data Lift f a = Pure a | Other (f a)
+
+instance (Eq1 f) => Eq1 (Lift f) where
+    liftEq eq (Pure x1) (Pure x2) = eq x1 x2
+    liftEq _ (Pure _) (Other _) = False
+    liftEq _ (Other _) (Pure _) = False
+    liftEq eq (Other y1) (Other y2) = liftEq eq y1 y2
+    {-# INLINE liftEq #-}
+
+instance (Ord1 f) => Ord1 (Lift f) where
+    liftCompare comp (Pure x1) (Pure x2) = comp x1 x2
+    liftCompare _ (Pure _) (Other _) = LT
+    liftCompare _ (Other _) (Pure _) = GT
+    liftCompare comp (Other y1) (Other y2) = liftCompare comp y1 y2
+    {-# INLINE liftCompare #-}
+
+instance (Read1 f) => Read1 (Lift f) where
+    liftReadsPrec rp rl = readsData $
+        readsUnaryWith rp "Pure" Pure `mappend`
+        readsUnaryWith (liftReadsPrec rp rl) "Other" Other
+
+instance (Show1 f) => Show1 (Lift f) where
+    liftShowsPrec sp _ d (Pure x) = showsUnaryWith sp "Pure" d x
+    liftShowsPrec sp sl d (Other y) =
+        showsUnaryWith (liftShowsPrec sp sl) "Other" d y
+
+instance (Eq1 f, Eq a) => Eq (Lift f a) where (==) = eq1
+instance (Ord1 f, Ord a) => Ord (Lift f a) where compare = compare1
+instance (Read1 f, Read a) => Read (Lift f a) where readsPrec = readsPrec1
+instance (Show1 f, Show a) => Show (Lift f a) where showsPrec = showsPrec1
+
+instance (Functor f) => Functor (Lift f) where
+    fmap f (Pure x) = Pure (f x)
+    fmap f (Other y) = Other (fmap f y)
+    {-# INLINE fmap #-}
+
+instance (Foldable f) => Foldable (Lift f) where
+    foldMap f (Pure x) = f x
+    foldMap f (Other y) = foldMap f y
+    {-# INLINE foldMap #-}
+
+instance (Traversable f) => Traversable (Lift f) where
+    traverse f (Pure x) = Pure <$> f x
+    traverse f (Other y) = Other <$> traverse f y
+    {-# INLINE traverse #-}
+
+-- | A combination is 'Pure' only if both parts are.
+instance (Applicative f) => Applicative (Lift f) where
+    pure = Pure
+    {-# INLINE pure #-}
+    Pure f <*> Pure x = Pure (f x)
+    Pure f <*> Other y = Other (f <$> y)
+    Other f <*> Pure x = Other (($ x) <$> f)
+    Other f <*> Other y = Other (f <*> y)
+    {-# INLINE (<*>) #-}
+
+-- | A combination is 'Pure' only either part is.
+instance (Alternative f) => Alternative (Lift f) where
+    empty = Other empty
+    {-# INLINE empty #-}
+    Pure x <|> _ = Pure x
+    Other _ <|> Pure y = Pure y
+    Other x <|> Other y = Other (x <|> y)
+    {-# INLINE (<|>) #-}
+
+-- | Projection to the other functor.
+unLift :: (Applicative f) => Lift f a -> f a
+unLift (Pure x) = pure x
+unLift (Other e) = e
+{-# INLINE unLift #-}
+
+-- | Apply a transformation to the other computation.
+mapLift :: (f a -> g a) -> Lift f a -> Lift g a
+mapLift _ (Pure x) = Pure x
+mapLift f (Other e) = Other (f e)
+{-# INLINE mapLift #-}
+
+-- | Eliminator for 'Lift'.
+--
+-- * @'elimLift' f g . 'pure' = f@
+--
+-- * @'elimLift' f g . 'Other' = g@
+--
+elimLift :: (a -> r) -> (f a -> r) -> Lift f a -> r
+elimLift f _ (Pure x) = f x
+elimLift _ g (Other e) = g e
+{-# INLINE elimLift #-}
+
+-- | An applicative functor that collects a monoid (e.g. lists) of errors.
+-- A sequence of computations fails if any of its components do, but
+-- unlike monads made with 'ExceptT' from "Control.Monad.Trans.Except",
+-- these computations continue after an error, collecting all the errors.
+--
+-- * @'pure' f '<*>' 'pure' x = 'pure' (f x)@
+--
+-- * @'pure' f '<*>' 'failure' e = 'failure' e@
+--
+-- * @'failure' e '<*>' 'pure' x = 'failure' e@
+--
+-- * @'failure' e1 '<*>' 'failure' e2 = 'failure' (e1 '<>' e2)@
+--
+type Errors e = Lift (Constant e)
+
+-- | Extractor for computations with accumulating errors.
+--
+-- * @'runErrors' ('pure' x) = 'Right' x@
+--
+-- * @'runErrors' ('failure' e) = 'Left' e@
+--
+runErrors :: Errors e a -> Either e a
+runErrors (Other (Constant e)) = Left e
+runErrors (Pure x) = Right x
+{-# INLINE runErrors #-}
+
+-- | Report an error.
+failure :: e -> Errors e a
+failure e = Other (Constant e)
+{-# INLINE failure #-}
+
+-- | Convert from 'Either' to 'Errors' (inverse of 'runErrors').
+eitherToErrors :: Either e a -> Errors e a
+eitherToErrors = either failure Pure

third_party/bazel/rules_haskell/examples/transformers/Control/Monad/Signatures.hs

@@ -0,0 +1,56 @@
+{-# LANGUAGE CPP #-}
+#if __GLASGOW_HASKELL__ >= 702
+{-# LANGUAGE Safe #-}
+#endif
+#if __GLASGOW_HASKELL__ >= 706
+{-# LANGUAGE PolyKinds #-}
+#endif
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Control.Monad.Signatures
+-- Copyright   :  (c) Ross Paterson 2012
+-- License     :  BSD-style (see the file LICENSE)
+--
+-- Maintainer  :  R.Paterson@city.ac.uk
+-- Stability   :  experimental
+-- Portability :  portable
+--
+-- Signatures for monad operations that require specialized lifting.
+-- Each signature has a uniformity property that the lifting should satisfy.
+-----------------------------------------------------------------------------
+
+module Control.Monad.Signatures (
+    CallCC, Catch, Listen, Pass
+  ) where
+
+-- | Signature of the @callCC@ operation,
+-- introduced in "Control.Monad.Trans.Cont".
+-- Any lifting function @liftCallCC@ should satisfy
+--
+-- * @'lift' (f k) = f' ('lift' . k) => 'lift' (cf f) = liftCallCC cf f'@
+--
+type CallCC m a b = ((a -> m b) -> m a) -> m a
+
+-- | Signature of the @catchE@ operation,
+-- introduced in "Control.Monad.Trans.Except".
+-- Any lifting function @liftCatch@ should satisfy
+--
+-- * @'lift' (cf m f) = liftCatch ('lift' . cf) ('lift' f)@
+--
+type Catch e m a = m a -> (e -> m a) -> m a
+
+-- | Signature of the @listen@ operation,
+-- introduced in "Control.Monad.Trans.Writer".
+-- Any lifting function @liftListen@ should satisfy
+--
+-- * @'lift' . liftListen = liftListen . 'lift'@
+--
+type Listen w m a = m a -> m (a, w)
+
+-- | Signature of the @pass@ operation,
+-- introduced in "Control.Monad.Trans.Writer".
+-- Any lifting function @liftPass@ should satisfy
+--
+-- * @'lift' . liftPass = liftPass . 'lift'@
+--
+type Pass w m a =  m (a, w -> w) -> m a

third_party/bazel/rules_haskell/examples/transformers/Control/Monad/Trans/Accum.hs

@@ -0,0 +1,292 @@
+{-# LANGUAGE CPP #-}
+#if __GLASGOW_HASKELL__ >= 702
+{-# LANGUAGE Safe #-}
+#endif
+#if __GLASGOW_HASKELL__ >= 710
+{-# LANGUAGE AutoDeriveTypeable #-}
+#endif
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Control.Monad.Trans.Accum
+-- Copyright   :  (c) Nickolay Kudasov 2016
+-- License     :  BSD-style (see the file LICENSE)
+--
+-- Maintainer  :  R.Paterson@city.ac.uk
+-- Stability   :  experimental
+-- Portability :  portable
+--
+-- The lazy 'AccumT' monad transformer, which adds accumulation
+-- capabilities (such as declarations or document patches) to a given monad.
+--
+-- This monad transformer provides append-only accumulation
+-- during the computation. For more general access, use
+-- "Control.Monad.Trans.State" instead.
+-----------------------------------------------------------------------------
+
+module Control.Monad.Trans.Accum (
+    -- * The Accum monad
+    Accum,
+    accum,
+    runAccum,
+    execAccum,
+    evalAccum,
+    mapAccum,
+    -- * The AccumT monad transformer
+    AccumT(AccumT),
+    runAccumT,
+    execAccumT,
+    evalAccumT,
+    mapAccumT,
+    -- * Accum operations
+    look,
+    looks,
+    add,
+    -- * Lifting other operations
+    liftCallCC,
+    liftCallCC',
+    liftCatch,
+    liftListen,
+    liftPass,
+    -- * Monad transformations
+    readerToAccumT,
+    writerToAccumT,
+    accumToStateT,
+  ) where
+
+import Control.Monad.IO.Class
+import Control.Monad.Trans.Class
+import Control.Monad.Trans.Reader (ReaderT(..))
+import Control.Monad.Trans.Writer (WriterT(..))
+import Control.Monad.Trans.State  (StateT(..))
+import Data.Functor.Identity
+
+import Control.Applicative
+import Control.Monad
+#if MIN_VERSION_base(4,9,0)
+import qualified Control.Monad.Fail as Fail
+#endif
+import Control.Monad.Fix
+import Control.Monad.Signatures
+#if !MIN_VERSION_base(4,8,0)
+import Data.Monoid
+#endif
+
+-- ---------------------------------------------------------------------------
+-- | An accumulation monad parameterized by the type @w@ of output to accumulate.
+--
+-- The 'return' function produces the output 'mempty', while @>>=@
+-- combines the outputs of the subcomputations using 'mappend'.
+type Accum w = AccumT w Identity
+
+-- | Construct an accumulation computation from a (result, output) pair.
+-- (The inverse of 'runAccum'.)
+accum :: (Monad m) => (w -> (a, w)) -> AccumT w m a
+accum f = AccumT $ \ w -> return (f w)
+{-# INLINE accum #-}
+
+-- | Unwrap an accumulation computation as a (result, output) pair.
+-- (The inverse of 'accum'.)
+runAccum :: Accum w a -> w -> (a, w)
+runAccum m = runIdentity . runAccumT m
+{-# INLINE runAccum #-}
+
+-- | Extract the output from an accumulation computation.
+--
+-- * @'execAccum' m w = 'snd' ('runAccum' m w)@
+execAccum :: Accum w a -> w -> w
+execAccum m w = snd (runAccum m w)
+{-# INLINE execAccum #-}
+
+-- | Evaluate an accumulation computation with the given initial output history
+-- and return the final value, discarding the final output.
+--
+-- * @'evalAccum' m w = 'fst' ('runAccum' m w)@
+evalAccum :: (Monoid w) => Accum w a -> w -> a
+evalAccum m w = fst (runAccum m w)
+{-# INLINE evalAccum #-}
+
+-- | Map both the return value and output of a computation using
+-- the given function.
+--
+-- * @'runAccum' ('mapAccum' f m) = f . 'runAccum' m@
+mapAccum :: ((a, w) -> (b, w)) -> Accum w a -> Accum w b
+mapAccum f = mapAccumT (Identity . f . runIdentity)
+{-# INLINE mapAccum #-}
+
+-- ---------------------------------------------------------------------------
+-- | An accumulation monad parameterized by:
+--
+--   * @w@ - the output to accumulate.
+--
+--   * @m@ - The inner monad.
+--
+-- The 'return' function produces the output 'mempty', while @>>=@
+-- combines the outputs of the subcomputations using 'mappend'.
+--
+-- This monad transformer is similar to both state and writer monad transformers.
+-- Thus it can be seen as
+--
+--  * a restricted append-only version of a state monad transformer or
+--
+--  * a writer monad transformer with the extra ability to read all previous output.
+newtype AccumT w m a = AccumT (w -> m (a, w))
+
+-- | Unwrap an accumulation computation.
+runAccumT :: AccumT w m a -> w -> m (a, w)
+runAccumT (AccumT f) = f
+{-# INLINE runAccumT #-}
+
+-- | Extract the output from an accumulation computation.
+--
+-- * @'execAccumT' m w = 'liftM' 'snd' ('runAccumT' m w)@
+execAccumT :: (Monad m) => AccumT w m a -> w -> m w
+execAccumT m w = do
+    ~(_, w') <- runAccumT m w
+    return w'
+{-# INLINE execAccumT #-}
+
+-- | Evaluate an accumulation computation with the given initial output history
+-- and return the final value, discarding the final output.
+--
+-- * @'evalAccumT' m w = 'liftM' 'fst' ('runAccumT' m w)@
+evalAccumT :: (Monad m, Monoid w) => AccumT w m a -> w -> m a
+evalAccumT m w = do
+    ~(a, _) <- runAccumT m w
+    return a
+{-# INLINE evalAccumT #-}
+
+-- | Map both the return value and output of a computation using
+-- the given function.
+--
+-- * @'runAccumT' ('mapAccumT' f m) = f . 'runAccumT' m@
+mapAccumT :: (m (a, w) -> n (b, w)) -> AccumT w m a -> AccumT w n b
+mapAccumT f m = AccumT (f . runAccumT m)
+{-# INLINE mapAccumT #-}
+
+instance (Functor m) => Functor (AccumT w m) where
+    fmap f = mapAccumT $ fmap $ \ ~(a, w) -> (f a, w)
+    {-# INLINE fmap #-}
+
+instance (Monoid w, Functor m, Monad m) => Applicative (AccumT w m) where
+    pure a  = AccumT $ const $ return (a, mempty)
+    {-# INLINE pure #-}
+    mf <*> mv = AccumT $ \ w -> do
+      ~(f, w')  <- runAccumT mf w
+      ~(v, w'') <- runAccumT mv (w `mappend` w')
+      return (f v, w' `mappend` w'')
+    {-# INLINE (<*>) #-}
+
+instance (Monoid w, Functor m, MonadPlus m) => Alternative (AccumT w m) where
+    empty   = AccumT $ const mzero
+    {-# INLINE empty #-}
+    m <|> n = AccumT $ \ w -> runAccumT m w `mplus` runAccumT n w
+    {-# INLINE (<|>) #-}
+
+instance (Monoid w, Functor m, Monad m) => Monad (AccumT w m) where
+#if !(MIN_VERSION_base(4,8,0))
+    return a  = AccumT $ const $ return (a, mempty)
+    {-# INLINE return #-}
+#endif
+    m >>= k  = AccumT $ \ w -> do
+        ~(a, w')  <- runAccumT m w
+        ~(b, w'') <- runAccumT (k a) (w `mappend` w')
+        return (b, w' `mappend` w'')
+    {-# INLINE (>>=) #-}
+#if !(MIN_VERSION_base(4,13,0))
+    fail msg = AccumT $ const (fail msg)
+    {-# INLINE fail #-}
+#endif
+
+#if MIN_VERSION_base(4,9,0)
+instance (Monoid w, Fail.MonadFail m) => Fail.MonadFail (AccumT w m) where
+    fail msg = AccumT $ const (Fail.fail msg)
+    {-# INLINE fail #-}
+#endif
+
+instance (Monoid w, Functor m, MonadPlus m) => MonadPlus (AccumT w m) where
+    mzero       = AccumT $ const mzero
+    {-# INLINE mzero #-}
+    m `mplus` n = AccumT $ \ w -> runAccumT m w `mplus` runAccumT n w
+    {-# INLINE mplus #-}
+
+instance (Monoid w, Functor m, MonadFix m) => MonadFix (AccumT w m) where
+    mfix m = AccumT $ \ w -> mfix $ \ ~(a, _) -> runAccumT (m a) w
+    {-# INLINE mfix #-}
+
+instance (Monoid w) => MonadTrans (AccumT w) where
+    lift m = AccumT $ const $ do
+        a <- m
+        return (a, mempty)
+    {-# INLINE lift #-}
+
+instance (Monoid w, Functor m, MonadIO m) => MonadIO (AccumT w m) where
+    liftIO = lift . liftIO
+    {-# INLINE liftIO #-}
+
+-- | @'look'@ is an action that fetches all the previously accumulated output.
+look :: (Monoid w, Monad m) => AccumT w m w
+look = AccumT $ \ w -> return (w, mempty)
+
+-- | @'look'@ is an action that retrieves a function of the previously accumulated output.
+looks :: (Monoid w, Monad m) => (w -> a) -> AccumT w m a
+looks f = AccumT $ \ w -> return (f w, mempty)
+
+-- | @'add' w@ is an action that produces the output @w@.
+add :: (Monad m) => w -> AccumT w m ()
+add w = accum $ const ((), w)
+{-# INLINE add #-}
+
+-- | Uniform lifting of a @callCC@ operation to the new monad.
+-- This version rolls back to the original output history on entering the
+-- continuation.
+liftCallCC :: CallCC m (a, w) (b, w) -> CallCC (AccumT w m) a b
+liftCallCC callCC f = AccumT $ \ w ->
+    callCC $ \ c ->
+    runAccumT (f (\ a -> AccumT $ \ _ -> c (a, w))) w
+{-# INLINE liftCallCC #-}
+
+-- | In-situ lifting of a @callCC@ operation to the new monad.
+-- This version uses the current output history on entering the continuation.
+-- It does not satisfy the uniformity property (see "Control.Monad.Signatures").
+liftCallCC' :: CallCC m (a, w) (b, w) -> CallCC (AccumT w m) a b
+liftCallCC' callCC f = AccumT $ \ s ->
+    callCC $ \ c ->
+    runAccumT (f (\ a -> AccumT $ \ s' -> c (a, s'))) s
+{-# INLINE liftCallCC' #-}
+
+-- | Lift a @catchE@ operation to the new monad.
+liftCatch :: Catch e m (a, w) -> Catch e (AccumT w m) a
+liftCatch catchE m h =
+    AccumT $ \ w -> runAccumT m w `catchE` \ e -> runAccumT (h e) w
+{-# INLINE liftCatch #-}
+
+-- | Lift a @listen@ operation to the new monad.
+liftListen :: (Monad m) => Listen w m (a, s) -> Listen w (AccumT s m) a
+liftListen listen m = AccumT $ \ s -> do
+    ~((a, s'), w) <- listen (runAccumT m s)
+    return ((a, w), s')
+{-# INLINE liftListen #-}
+
+-- | Lift a @pass@ operation to the new monad.
+liftPass :: (Monad m) => Pass w m (a, s) -> Pass w (AccumT s m) a
+liftPass pass m = AccumT $ \ s -> pass $ do
+    ~((a, f), s') <- runAccumT m s
+    return ((a, s'), f)
+{-# INLINE liftPass #-}
+
+-- | Convert a read-only computation into an accumulation computation.
+readerToAccumT :: (Functor m, Monoid w) => ReaderT w m a -> AccumT w m a
+readerToAccumT (ReaderT f) = AccumT $ \ w -> fmap (\ a -> (a, mempty)) (f w)
+{-# INLINE readerToAccumT #-}
+
+-- | Convert a writer computation into an accumulation computation.
+writerToAccumT :: WriterT w m a -> AccumT w m a
+writerToAccumT (WriterT m) = AccumT $ const $ m
+{-# INLINE writerToAccumT #-}
+
+-- | Convert an accumulation (append-only) computation into a fully
+-- stateful computation.
+accumToStateT :: (Functor m, Monoid s) => AccumT s m a -> StateT s m a
+accumToStateT (AccumT f) =
+    StateT $ \ w -> fmap (\ ~(a, w') -> (a, w `mappend` w')) (f w)
+{-# INLINE accumToStateT #-}

third_party/bazel/rules_haskell/examples/transformers/Control/Monad/Trans/Class.hs

@@ -0,0 +1,262 @@
+{-# LANGUAGE CPP #-}
+#if __GLASGOW_HASKELL__ >= 702
+{-# LANGUAGE Safe #-}
+#endif
+#if __GLASGOW_HASKELL__ >= 710
+{-# LANGUAGE AutoDeriveTypeable #-}
+#endif
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Control.Monad.Trans.Class
+-- Copyright   :  (c) Andy Gill 2001,
+--                (c) Oregon Graduate Institute of Science and Technology, 2001
+-- License     :  BSD-style (see the file LICENSE)
+--
+-- Maintainer  :  R.Paterson@city.ac.uk
+-- Stability   :  experimental
+-- Portability :  portable
+--
+-- The class of monad transformers.
+--
+-- A monad transformer makes a new monad out of an existing monad, such
+-- that computations of the old monad may be embedded in the new one.
+-- To construct a monad with a desired set of features, one typically
+-- starts with a base monad, such as 'Data.Functor.Identity.Identity', @[]@ or 'IO', and
+-- applies a sequence of monad transformers.
+-----------------------------------------------------------------------------
+
+module Control.Monad.Trans.Class (
+    -- * Transformer class
+    MonadTrans(..)
+
+    -- * Conventions
+    -- $conventions
+
+    -- * Strict monads
+    -- $strict
+
+    -- * Examples
+    -- ** Parsing
+    -- $example1
+
+    -- ** Parsing and counting
+    -- $example2
+
+    -- ** Interpreter monad
+    -- $example3
+  ) where
+
+-- | The class of monad transformers.  Instances should satisfy the
+-- following laws, which state that 'lift' is a monad transformation:
+--
+-- * @'lift' . 'return' = 'return'@
+--
+-- * @'lift' (m >>= f) = 'lift' m >>= ('lift' . f)@
+
+class MonadTrans t where
+    -- | Lift a computation from the argument monad to the constructed monad.
+    lift :: (Monad m) => m a -> t m a
+
+{- $conventions
+Most monad transformer modules include the special case of applying
+the transformer to 'Data.Functor.Identity.Identity'.  For example,
+@'Control.Monad.Trans.State.Lazy.State' s@ is an abbreviation for
+@'Control.Monad.Trans.State.Lazy.StateT' s 'Data.Functor.Identity.Identity'@.
+
+Each monad transformer also comes with an operation @run@/XXX/@T@ to
+unwrap the transformer, exposing a computation of the inner monad.
+(Currently these functions are defined as field labels, but in the next
+major release they will be separate functions.)
+
+All of the monad transformers except 'Control.Monad.Trans.Cont.ContT'
+and 'Control.Monad.Trans.Cont.SelectT' are functors on the category
+of monads: in addition to defining a mapping of monads, they
+also define a mapping from transformations between base monads to
+transformations between transformed monads, called @map@/XXX/@T@.
+Thus given a monad transformation @t :: M a -> N a@, the combinator
+'Control.Monad.Trans.State.Lazy.mapStateT' constructs a monad
+transformation
+
+> mapStateT t :: StateT s M a -> StateT s N a
+
+For these monad transformers, 'lift' is a natural transformation in the
+category of monads, i.e. for any monad transformation @t :: M a -> N a@,
+
+* @map@/XXX/@T t . 'lift' = 'lift' . t@
+
+Each of the monad transformers introduces relevant operations.
+In a sequence of monad transformers, most of these operations.can be
+lifted through other transformers using 'lift' or the @map@/XXX/@T@
+combinator, but a few with more complex type signatures require
+specialized lifting combinators, called @lift@/Op/
+(see "Control.Monad.Signatures").
+-}
+
+{- $strict
+
+A monad is said to be /strict/ if its '>>=' operation is strict in its first
+argument.  The base monads 'Maybe', @[]@ and 'IO' are strict:
+
+>>> undefined >> return 2 :: Maybe Integer
+*** Exception: Prelude.undefined
+
+However the monad 'Data.Functor.Identity.Identity' is not:
+
+>>> runIdentity (undefined >> return 2)
+2
+
+In a strict monad you know when each action is executed, but the monad
+is not necessarily strict in the return value, or in other components
+of the monad, such as a state.  However you can use 'seq' to create
+an action that is strict in the component you want evaluated.
+-}
+
+{- $example1
+
+The first example is a parser monad in the style of
+
+* \"Monadic parsing in Haskell\", by Graham Hutton and Erik Meijer,
+/Journal of Functional Programming/ 8(4):437-444, July 1998
+(<http://www.cs.nott.ac.uk/~pszgmh/bib.html#pearl>).
+
+We can define such a parser monad by adding a state (the 'String' remaining
+to be parsed) to the @[]@ monad, which provides non-determinism:
+
+> import Control.Monad.Trans.State
+>
+> type Parser = StateT String []
+
+Then @Parser@ is an instance of @MonadPlus@: monadic sequencing implements
+concatenation of parsers, while @mplus@ provides choice.  To use parsers,
+we need a primitive to run a constructed parser on an input string:
+
+> runParser :: Parser a -> String -> [a]
+> runParser p s = [x | (x, "") <- runStateT p s]
+
+Finally, we need a primitive parser that matches a single character,
+from which arbitrarily complex parsers may be constructed:
+
+> item :: Parser Char
+> item = do
+>     c:cs <- get
+>     put cs
+>     return c
+
+In this example we use the operations @get@ and @put@ from
+"Control.Monad.Trans.State", which are defined only for monads that are
+applications of 'Control.Monad.Trans.State.Lazy.StateT'.  Alternatively one
+could use monad classes from the @mtl@ package or similar, which contain
+methods @get@ and @put@ with types generalized over all suitable monads.
+-}
+
+{- $example2
+
+We can define a parser that also counts by adding a
+'Control.Monad.Trans.Writer.Lazy.WriterT' transformer:
+
+> import Control.Monad.Trans.Class
+> import Control.Monad.Trans.State
+> import Control.Monad.Trans.Writer
+> import Data.Monoid
+>
+> type Parser = WriterT (Sum Int) (StateT String [])
+
+The function that applies a parser must now unwrap each of the monad
+transformers in turn:
+
+> runParser :: Parser a -> String -> [(a, Int)]
+> runParser p s = [(x, n) | ((x, Sum n), "") <- runStateT (runWriterT p) s]
+
+To define the @item@ parser, we need to lift the
+'Control.Monad.Trans.State.Lazy.StateT' operations through the
+'Control.Monad.Trans.Writer.Lazy.WriterT' transformer.
+
+> item :: Parser Char
+> item = do
+>     c:cs <- lift get
+>     lift (put cs)
+>     return c
+
+In this case, we were able to do this with 'lift', but operations with
+more complex types require special lifting functions, which are provided
+by monad transformers for which they can be implemented.  If you use the
+monad classes of the @mtl@ package or similar, this lifting is handled
+automatically by the instances of the classes, and you need only use
+the generalized methods @get@ and @put@.
+
+We can also define a primitive using the Writer:
+
+> tick :: Parser ()
+> tick = tell (Sum 1)
+
+Then the parser will keep track of how many @tick@s it executes.
+-}
+
+{- $example3
+
+This example is a cut-down version of the one in
+
+* \"Monad Transformers and Modular Interpreters\",
+by Sheng Liang, Paul Hudak and Mark Jones in /POPL'95/
+(<http://web.cecs.pdx.edu/~mpj/pubs/modinterp.html>).
+
+Suppose we want to define an interpreter that can do I\/O and has
+exceptions, an environment and a modifiable store.  We can define
+a monad that supports all these things as a stack of monad transformers:
+
+> import Control.Monad.Trans.Class
+> import Control.Monad.Trans.State
+> import qualified Control.Monad.Trans.Reader as R
+> import qualified Control.Monad.Trans.Except as E
+> import Control.Monad.IO.Class
+>
+> type InterpM = StateT Store (R.ReaderT Env (E.ExceptT Err IO))
+
+for suitable types @Store@, @Env@ and @Err@.
+
+Now we would like to be able to use the operations associated with each
+of those monad transformers on @InterpM@ actions.  Since the uppermost
+monad transformer of @InterpM@ is 'Control.Monad.Trans.State.Lazy.StateT',
+it already has the state operations @get@ and @set@.
+
+The first of the 'Control.Monad.Trans.Reader.ReaderT' operations,
+'Control.Monad.Trans.Reader.ask', is a simple action, so we can lift it
+through 'Control.Monad.Trans.State.Lazy.StateT' to @InterpM@ using 'lift':
+
+> ask :: InterpM Env
+> ask = lift R.ask
+
+The other 'Control.Monad.Trans.Reader.ReaderT' operation,
+'Control.Monad.Trans.Reader.local', has a suitable type for lifting
+using 'Control.Monad.Trans.State.Lazy.mapStateT':
+
+> local :: (Env -> Env) -> InterpM a -> InterpM a
+> local f = mapStateT (R.local f)
+
+We also wish to lift the operations of 'Control.Monad.Trans.Except.ExceptT'
+through both 'Control.Monad.Trans.Reader.ReaderT' and
+'Control.Monad.Trans.State.Lazy.StateT'.  For the operation
+'Control.Monad.Trans.Except.throwE', we know @throwE e@ is a simple
+action, so we can lift it through the two monad transformers to @InterpM@
+with two 'lift's:
+
+> throwE :: Err -> InterpM a
+> throwE e = lift (lift (E.throwE e))
+
+The 'Control.Monad.Trans.Except.catchE' operation has a more
+complex type, so we need to use the special-purpose lifting function
+@liftCatch@ provided by most monad transformers.  Here we use
+the 'Control.Monad.Trans.Reader.ReaderT' version followed by the
+'Control.Monad.Trans.State.Lazy.StateT' version:
+
+> catchE :: InterpM a -> (Err -> InterpM a) -> InterpM a
+> catchE = liftCatch (R.liftCatch E.catchE)
+
+We could lift 'IO' actions to @InterpM@ using three 'lift's, but @InterpM@
+is automatically an instance of 'Control.Monad.IO.Class.MonadIO',
+so we can use 'Control.Monad.IO.Class.liftIO' instead:
+
+> putStr :: String -> InterpM ()
+> putStr s = liftIO (Prelude.putStr s)
+
+-}

third_party/bazel/rules_haskell/examples/transformers/Control/Monad/Trans/Cont.hs

@@ -0,0 +1,240 @@
+{-# LANGUAGE CPP #-}
+#if __GLASGOW_HASKELL__ >= 702
+{-# LANGUAGE Safe #-}
+#endif
+#if __GLASGOW_HASKELL__ >= 706
+{-# LANGUAGE PolyKinds #-}
+#endif
+#if __GLASGOW_HASKELL__ >= 710
+{-# LANGUAGE AutoDeriveTypeable #-}
+#endif
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Control.Monad.Trans.Cont
+-- Copyright   :  (c) The University of Glasgow 2001
+-- License     :  BSD-style (see the file LICENSE)
+--
+-- Maintainer  :  R.Paterson@city.ac.uk
+-- Stability   :  experimental
+-- Portability :  portable
+--
+-- Continuation monads.
+--
+-- Delimited continuation operators are taken from Kenichi Asai and Oleg
+-- Kiselyov's tutorial at CW 2011, \"Introduction to programming with
+-- shift and reset\" (<http://okmij.org/ftp/continuations/#tutorial>).
+--
+-----------------------------------------------------------------------------
+
+module Control.Monad.Trans.Cont (
+    -- * The Cont monad
+    Cont,
+    cont,
+    runCont,
+    evalCont,
+    mapCont,
+    withCont,
+    -- ** Delimited continuations
+    reset, shift,
+    -- * The ContT monad transformer
+    ContT(..),
+    evalContT,
+    mapContT,
+    withContT,
+    callCC,
+    -- ** Delimited continuations
+    resetT, shiftT,
+    -- * Lifting other operations
+    liftLocal,
+  ) where
+
+import Control.Monad.IO.Class
+import Control.Monad.Trans.Class
+import Data.Functor.Identity
+
+import Control.Applicative
+#if MIN_VERSION_base(4,9,0)
+import qualified Control.Monad.Fail as Fail
+#endif
+
+{- |
+Continuation monad.
+@Cont r a@ is a CPS ("continuation-passing style") computation that produces an
+intermediate result of type @a@ within a CPS computation whose final result type
+is @r@.
+
+The @return@ function simply creates a continuation which passes the value on.
+
+The @>>=@ operator adds the bound function into the continuation chain.
+-}
+type Cont r = ContT r Identity
+
+-- | Construct a continuation-passing computation from a function.
+-- (The inverse of 'runCont')
+cont :: ((a -> r) -> r) -> Cont r a
+cont f = ContT (\ c -> Identity (f (runIdentity . c)))
+{-# INLINE cont #-}
+
+-- | The result of running a CPS computation with a given final continuation.
+-- (The inverse of 'cont')
+runCont
+    :: Cont r a         -- ^ continuation computation (@Cont@).
+    -> (a -> r)         -- ^ the final continuation, which produces
+                        -- the final result (often 'id').
+    -> r
+runCont m k = runIdentity (runContT m (Identity . k))
+{-# INLINE runCont #-}
+
+-- | The result of running a CPS computation with the identity as the
+-- final continuation.
+--
+-- * @'evalCont' ('return' x) = x@
+evalCont :: Cont r r -> r
+evalCont m = runIdentity (evalContT m)
+{-# INLINE evalCont #-}
+
+-- | Apply a function to transform the result of a continuation-passing
+-- computation.
+--
+-- * @'runCont' ('mapCont' f m) = f . 'runCont' m@
+mapCont :: (r -> r) -> Cont r a -> Cont r a
+mapCont f = mapContT (Identity . f . runIdentity)
+{-# INLINE mapCont #-}
+
+-- | Apply a function to transform the continuation passed to a CPS
+-- computation.
+--
+-- * @'runCont' ('withCont' f m) = 'runCont' m . f@
+withCont :: ((b -> r) -> (a -> r)) -> Cont r a -> Cont r b
+withCont f = withContT ((Identity .) . f . (runIdentity .))
+{-# INLINE withCont #-}
+
+-- | @'reset' m@ delimits the continuation of any 'shift' inside @m@.
+--
+-- * @'reset' ('return' m) = 'return' m@
+--
+reset :: Cont r r -> Cont r' r
+reset = resetT
+{-# INLINE reset #-}
+
+-- | @'shift' f@ captures the continuation up to the nearest enclosing
+-- 'reset' and passes it to @f@:
+--
+-- * @'reset' ('shift' f >>= k) = 'reset' (f ('evalCont' . k))@
+--
+shift :: ((a -> r) -> Cont r r) -> Cont r a
+shift f = shiftT (f . (runIdentity .))
+{-# INLINE shift #-}
+
+-- | The continuation monad transformer.
+-- Can be used to add continuation handling to any type constructor:
+-- the 'Monad' instance and most of the operations do not require @m@
+-- to be a monad.
+--
+-- 'ContT' is not a functor on the category of monads, and many operations
+-- cannot be lifted through it.
+newtype ContT r m a = ContT { runContT :: (a -> m r) -> m r }
+
+-- | The result of running a CPS computation with 'return' as the
+-- final continuation.
+--
+-- * @'evalContT' ('lift' m) = m@
+evalContT :: (Monad m) => ContT r m r -> m r
+evalContT m = runContT m return
+{-# INLINE evalContT #-}
+
+-- | Apply a function to transform the result of a continuation-passing
+-- computation.  This has a more restricted type than the @map@ operations
+-- for other monad transformers, because 'ContT' does not define a functor
+-- in the category of monads.
+--
+-- * @'runContT' ('mapContT' f m) = f . 'runContT' m@
+mapContT :: (m r -> m r) -> ContT r m a -> ContT r m a
+mapContT f m = ContT $ f . runContT m
+{-# INLINE mapContT #-}
+
+-- | Apply a function to transform the continuation passed to a CPS
+-- computation.
+--
+-- * @'runContT' ('withContT' f m) = 'runContT' m . f@
+withContT :: ((b -> m r) -> (a -> m r)) -> ContT r m a -> ContT r m b
+withContT f m = ContT $ runContT m . f
+{-# INLINE withContT #-}
+
+instance Functor (ContT r m) where
+    fmap f m = ContT $ \ c -> runContT m (c . f)
+    {-# INLINE fmap #-}
+
+instance Applicative (ContT r m) where
+    pure x  = ContT ($ x)
+    {-# INLINE pure #-}
+    f <*> v = ContT $ \ c -> runContT f $ \ g -> runContT v (c . g)
+    {-# INLINE (<*>) #-}
+    m *> k = m >>= \_ -> k
+    {-# INLINE (*>) #-}
+
+instance Monad (ContT r m) where
+#if !(MIN_VERSION_base(4,8,0))
+    return x = ContT ($ x)
+    {-# INLINE return #-}
+#endif
+    m >>= k  = ContT $ \ c -> runContT m (\ x -> runContT (k x) c)
+    {-# INLINE (>>=) #-}
+
+#if MIN_VERSION_base(4,9,0)
+instance (Fail.MonadFail m) => Fail.MonadFail (ContT r m) where
+    fail msg = ContT $ \ _ -> Fail.fail msg
+    {-# INLINE fail #-}
+#endif
+
+instance MonadTrans (ContT r) where
+    lift m = ContT (m >>=)
+    {-# INLINE lift #-}
+
+instance (MonadIO m) => MonadIO (ContT r m) where
+    liftIO = lift . liftIO
+    {-# INLINE liftIO #-}
+
+-- | @callCC@ (call-with-current-continuation) calls its argument
+-- function, passing it the current continuation.  It provides
+-- an escape continuation mechanism for use with continuation
+-- monads.  Escape continuations one allow to abort the current
+-- computation and return a value immediately.  They achieve
+-- a similar effect to 'Control.Monad.Trans.Except.throwE'
+-- and 'Control.Monad.Trans.Except.catchE' within an
+-- 'Control.Monad.Trans.Except.ExceptT' monad.  The advantage of this
+-- function over calling 'return' is that it makes the continuation
+-- explicit, allowing more flexibility and better control.
+--
+-- The standard idiom used with @callCC@ is to provide a lambda-expression
+-- to name the continuation. Then calling the named continuation anywhere
+-- within its scope will escape from the computation, even if it is many
+-- layers deep within nested computations.
+callCC :: ((a -> ContT r m b) -> ContT r m a) -> ContT r m a
+callCC f = ContT $ \ c -> runContT (f (\ x -> ContT $ \ _ -> c x)) c
+{-# INLINE callCC #-}
+
+-- | @'resetT' m@ delimits the continuation of any 'shiftT' inside @m@.
+--
+-- * @'resetT' ('lift' m) = 'lift' m@
+--
+resetT :: (Monad m) => ContT r m r -> ContT r' m r
+resetT = lift . evalContT
+{-# INLINE resetT #-}
+
+-- | @'shiftT' f@ captures the continuation up to the nearest enclosing
+-- 'resetT' and passes it to @f@:
+--
+-- * @'resetT' ('shiftT' f >>= k) = 'resetT' (f ('evalContT' . k))@
+--
+shiftT :: (Monad m) => ((a -> m r) -> ContT r m r) -> ContT r m a
+shiftT f = ContT (evalContT . f)
+{-# INLINE shiftT #-}
+
+-- | @'liftLocal' ask local@ yields a @local@ function for @'ContT' r m@.
+liftLocal :: (Monad m) => m r' -> ((r' -> r') -> m r -> m r) ->
+    (r' -> r') -> ContT r m a -> ContT r m a
+liftLocal ask local f m = ContT $ \ c -> do
+    r <- ask
+    local f (runContT m (local (const r) . c))
+{-# INLINE liftLocal #-}

third_party/bazel/rules_haskell/examples/transformers/Control/Monad/Trans/Error.hs

@@ -0,0 +1,333 @@
+{-# LANGUAGE CPP #-}
+#if __GLASGOW_HASKELL__ >= 702
+{-# LANGUAGE Safe #-}
+#endif
+#if __GLASGOW_HASKELL__ >= 710
+{-# LANGUAGE AutoDeriveTypeable #-}
+#endif
+#if !(MIN_VERSION_base(4,9,0))
+{-# OPTIONS_GHC -fno-warn-orphans #-}
+#endif
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Control.Monad.Trans.Error
+-- Copyright   :  (c) Michael Weber <michael.weber@post.rwth-aachen.de> 2001,
+--                (c) Jeff Newbern 2003-2006,
+--                (c) Andriy Palamarchuk 2006
+-- License     :  BSD-style (see the file LICENSE)
+--
+-- Maintainer  :  R.Paterson@city.ac.uk
+-- Stability   :  experimental
+-- Portability :  portable
+--
+-- This monad transformer adds the ability to fail or throw exceptions
+-- to a monad.
+--
+-- A sequence of actions succeeds, producing a value, only if all the
+-- actions in the sequence are successful.  If one fails with an error,
+-- the rest of the sequence is skipped and the composite action fails
+-- with that error.
+--
+-- If the value of the error is not required, the variant in
+-- "Control.Monad.Trans.Maybe" may be used instead.
+--
+-- /Note:/ This module will be removed in a future release.
+-- Instead, use "Control.Monad.Trans.Except", which does not restrict
+-- the exception type, and also includes a base exception monad.
+-----------------------------------------------------------------------------
+
+module Control.Monad.Trans.Error
+  {-# DEPRECATED "Use Control.Monad.Trans.Except instead" #-} (
+    -- * The ErrorT monad transformer
+    Error(..),
+    ErrorList(..),
+    ErrorT(..),
+    mapErrorT,
+    -- * Error operations
+    throwError,
+    catchError,
+    -- * Lifting other operations
+    liftCallCC,
+    liftListen,
+    liftPass,
+    -- * Examples
+    -- $examples
+  ) where
+
+import Control.Monad.IO.Class
+import Control.Monad.Signatures
+import Control.Monad.Trans.Class
+import Data.Functor.Classes
+#if MIN_VERSION_base(4,12,0)
+import Data.Functor.Contravariant
+#endif
+
+import Control.Applicative
+import Control.Exception (IOException)
+import Control.Monad
+#if MIN_VERSION_base(4,9,0)
+import qualified Control.Monad.Fail as Fail
+#endif
+import Control.Monad.Fix
+#if !(MIN_VERSION_base(4,6,0))
+import Control.Monad.Instances ()  -- deprecated from base-4.6
+#endif
+import Data.Foldable (Foldable(foldMap))
+import Data.Monoid (mempty)
+import Data.Traversable (Traversable(traverse))
+import System.IO.Error
+
+#if !(MIN_VERSION_base(4,9,0))
+-- These instances are in base-4.9.0
+
+instance MonadPlus IO where
+    mzero       = ioError (userError "mzero")
+    m `mplus` n = m `catchIOError` \ _ -> n
+
+instance Alternative IO where
+    empty = mzero
+    (<|>) = mplus
+
+# if !(MIN_VERSION_base(4,4,0))
+-- exported by System.IO.Error from base-4.4
+catchIOError :: IO a -> (IOError -> IO a) -> IO a
+catchIOError = catch
+# endif
+#endif
+
+instance (Error e) => Alternative (Either e) where
+    empty        = Left noMsg
+    Left _ <|> n = n
+    m      <|> _ = m
+
+instance (Error e) => MonadPlus (Either e) where
+    mzero            = Left noMsg
+    Left _ `mplus` n = n
+    m      `mplus` _ = m
+
+#if !(MIN_VERSION_base(4,3,0))
+-- These instances are in base-4.3
+
+instance Applicative (Either e) where
+    pure          = Right
+    Left  e <*> _ = Left e
+    Right f <*> r = fmap f r
+
+instance Monad (Either e) where
+    return        = Right
+    Left  l >>= _ = Left l
+    Right r >>= k = k r
+
+instance MonadFix (Either e) where
+    mfix f = let
+        a = f $ case a of
+            Right r -> r
+            _       -> error "empty mfix argument"
+        in a
+
+#endif /* base to 4.2.0.x */
+
+-- | An exception to be thrown.
+--
+-- Minimal complete definition: 'noMsg' or 'strMsg'.
+class Error a where
+    -- | Creates an exception without a message.
+    -- The default implementation is @'strMsg' \"\"@.
+    noMsg  :: a
+    -- | Creates an exception with a message.
+    -- The default implementation of @'strMsg' s@ is 'noMsg'.
+    strMsg :: String -> a
+
+    noMsg    = strMsg ""
+    strMsg _ = noMsg
+
+instance Error IOException where
+    strMsg = userError
+
+-- | A string can be thrown as an error.
+instance (ErrorList a) => Error [a] where
+    strMsg = listMsg
+
+-- | Workaround so that we can have a Haskell 98 instance @'Error' 'String'@.
+class ErrorList a where
+    listMsg :: String -> [a]
+
+instance ErrorList Char where
+    listMsg = id
+
+-- | The error monad transformer. It can be used to add error handling
+-- to other monads.
+--
+-- The @ErrorT@ Monad structure is parameterized over two things:
+--
+-- * e - The error type.
+--
+-- * m - The inner monad.
+--
+-- The 'return' function yields a successful computation, while @>>=@
+-- sequences two subcomputations, failing on the first error.
+newtype ErrorT e m a = ErrorT { runErrorT :: m (Either e a) }
+
+instance (Eq e, Eq1 m) => Eq1 (ErrorT e m) where
+    liftEq eq (ErrorT x) (ErrorT y) = liftEq (liftEq eq) x y
+
+instance (Ord e, Ord1 m) => Ord1 (ErrorT e m) where
+    liftCompare comp (ErrorT x) (ErrorT y) = liftCompare (liftCompare comp) x y
+
+instance (Read e, Read1 m) => Read1 (ErrorT e m) where
+    liftReadsPrec rp rl = readsData $
+        readsUnaryWith (liftReadsPrec rp' rl') "ErrorT" ErrorT
+      where
+        rp' = liftReadsPrec rp rl
+        rl' = liftReadList rp rl
+
+instance (Show e, Show1 m) => Show1 (ErrorT e m) where
+    liftShowsPrec sp sl d (ErrorT m) =
+        showsUnaryWith (liftShowsPrec sp' sl') "ErrorT" d m
+      where
+        sp' = liftShowsPrec sp sl
+        sl' = liftShowList sp sl
+
+instance (Eq e, Eq1 m, Eq a) => Eq (ErrorT e m a) where (==) = eq1
+instance (Ord e, Ord1 m, Ord a) => Ord (ErrorT e m a) where compare = compare1
+instance (Read e, Read1 m, Read a) => Read (ErrorT e m a) where
+    readsPrec = readsPrec1
+instance (Show e, Show1 m, Show a) => Show (ErrorT e m a) where
+    showsPrec = showsPrec1
+
+-- | Map the unwrapped computation using the given function.
+--
+-- * @'runErrorT' ('mapErrorT' f m) = f ('runErrorT' m)@
+mapErrorT :: (m (Either e a) -> n (Either e' b))
+          -> ErrorT e m a
+          -> ErrorT e' n b
+mapErrorT f m = ErrorT $ f (runErrorT m)
+
+instance (Functor m) => Functor (ErrorT e m) where
+    fmap f = ErrorT . fmap (fmap f) . runErrorT
+
+instance (Foldable f) => Foldable (ErrorT e f) where
+    foldMap f (ErrorT a) = foldMap (either (const mempty) f) a
+
+instance (Traversable f) => Traversable (ErrorT e f) where
+    traverse f (ErrorT a) =
+        ErrorT <$> traverse (either (pure . Left) (fmap Right . f)) a
+
+instance (Functor m, Monad m) => Applicative (ErrorT e m) where
+    pure a  = ErrorT $ return (Right a)
+    f <*> v = ErrorT $ do
+        mf <- runErrorT f
+        case mf of
+            Left  e -> return (Left e)
+            Right k -> do
+                mv <- runErrorT v
+                case mv of
+                    Left  e -> return (Left e)
+                    Right x -> return (Right (k x))
+
+instance (Functor m, Monad m, Error e) => Alternative (ErrorT e m) where
+    empty = mzero
+    (<|>) = mplus
+
+instance (Monad m, Error e) => Monad (ErrorT e m) where
+#if !(MIN_VERSION_base(4,8,0))
+    return a = ErrorT $ return (Right a)
+#endif
+    m >>= k  = ErrorT $ do
+        a <- runErrorT m
+        case a of
+            Left  l -> return (Left l)
+            Right r -> runErrorT (k r)
+#if !(MIN_VERSION_base(4,13,0))
+    fail msg = ErrorT $ return (Left (strMsg msg))
+#endif
+
+#if MIN_VERSION_base(4,9,0)
+instance (Monad m, Error e) => Fail.MonadFail (ErrorT e m) where
+    fail msg = ErrorT $ return (Left (strMsg msg))
+#endif
+
+instance (Monad m, Error e) => MonadPlus (ErrorT e m) where
+    mzero       = ErrorT $ return (Left noMsg)
+    m `mplus` n = ErrorT $ do
+        a <- runErrorT m
+        case a of
+            Left  _ -> runErrorT n
+            Right r -> return (Right r)
+
+instance (MonadFix m, Error e) => MonadFix (ErrorT e m) where
+    mfix f = ErrorT $ mfix $ \ a -> runErrorT $ f $ case a of
+        Right r -> r
+        _       -> error "empty mfix argument"
+
+instance MonadTrans (ErrorT e) where
+    lift m = ErrorT $ do
+        a <- m
+        return (Right a)
+
+instance (Error e, MonadIO m) => MonadIO (ErrorT e m) where
+    liftIO = lift . liftIO
+
+#if MIN_VERSION_base(4,12,0)
+instance Contravariant m => Contravariant (ErrorT e m) where
+    contramap f = ErrorT . contramap (fmap f) . runErrorT
+#endif
+
+-- | Signal an error value @e@.
+--
+-- * @'runErrorT' ('throwError' e) = 'return' ('Left' e)@
+--
+-- * @'throwError' e >>= m = 'throwError' e@
+throwError :: (Monad m) => e -> ErrorT e m a
+throwError l = ErrorT $ return (Left l)
+
+-- | Handle an error.
+--
+-- * @'catchError' h ('lift' m) = 'lift' m@
+--
+-- * @'catchError' h ('throwError' e) = h e@
+catchError :: (Monad m) =>
+    ErrorT e m a                -- ^ the inner computation
+    -> (e -> ErrorT e m a)      -- ^ a handler for errors in the inner
+                                -- computation
+    -> ErrorT e m a
+m `catchError` h = ErrorT $ do
+    a <- runErrorT m
+    case a of
+        Left  l -> runErrorT (h l)
+        Right r -> return (Right r)
+
+-- | Lift a @callCC@ operation to the new monad.
+liftCallCC :: CallCC m (Either e a) (Either e b) -> CallCC (ErrorT e m) a b
+liftCallCC callCC f = ErrorT $
+    callCC $ \ c ->
+    runErrorT (f (\ a -> ErrorT $ c (Right a)))
+
+-- | Lift a @listen@ operation to the new monad.
+liftListen :: (Monad m) => Listen w m (Either e a) -> Listen w (ErrorT e m) a
+liftListen listen = mapErrorT $ \ m -> do
+    (a, w) <- listen m
+    return $! fmap (\ r -> (r, w)) a
+
+-- | Lift a @pass@ operation to the new monad.
+liftPass :: (Monad m) => Pass w m (Either e a) -> Pass w (ErrorT e m) a
+liftPass pass = mapErrorT $ \ m -> pass $ do
+    a <- m
+    return $! case a of
+        Left  l      -> (Left  l, id)
+        Right (r, f) -> (Right r, f)
+
+{- $examples
+
+Wrapping an IO action that can throw an error @e@:
+
+> type ErrorWithIO e a = ErrorT e IO a
+> ==> ErrorT (IO (Either e a))
+
+An IO monad wrapped in @StateT@ inside of @ErrorT@:
+
+> type ErrorAndStateWithIO e s a = ErrorT e (StateT s IO) a
+> ==> ErrorT (StateT s IO (Either e a))
+> ==> ErrorT (StateT (s -> IO (Either e a,s)))
+
+-}

third_party/bazel/rules_haskell/examples/transformers/Control/Monad/Trans/Except.hs

@@ -0,0 +1,316 @@
+{-# LANGUAGE CPP #-}
+#if __GLASGOW_HASKELL__ >= 702
+{-# LANGUAGE Safe #-}
+#endif
+#if __GLASGOW_HASKELL__ >= 710
+{-# LANGUAGE AutoDeriveTypeable #-}
+#endif
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Control.Monad.Trans.Except
+-- Copyright   :  (C) 2013 Ross Paterson
+-- License     :  BSD-style (see the file LICENSE)
+--
+-- Maintainer  :  R.Paterson@city.ac.uk
+-- Stability   :  experimental
+-- Portability :  portable
+--
+-- This monad transformer extends a monad with the ability to throw exceptions.
+--
+-- A sequence of actions terminates normally, producing a value,
+-- only if none of the actions in the sequence throws an exception.
+-- If one throws an exception, the rest of the sequence is skipped and
+-- the composite action exits with that exception.
+--
+-- If the value of the exception is not required, the variant in
+-- "Control.Monad.Trans.Maybe" may be used instead.
+-----------------------------------------------------------------------------
+
+module Control.Monad.Trans.Except (
+    -- * The Except monad
+    Except,
+    except,
+    runExcept,
+    mapExcept,
+    withExcept,
+    -- * The ExceptT monad transformer
+    ExceptT(ExceptT),
+    runExceptT,
+    mapExceptT,
+    withExceptT,
+    -- * Exception operations
+    throwE,
+    catchE,
+    -- * Lifting other operations
+    liftCallCC,
+    liftListen,
+    liftPass,
+  ) where
+
+import Control.Monad.IO.Class
+import Control.Monad.Signatures
+import Control.Monad.Trans.Class
+import Data.Functor.Classes
+#if MIN_VERSION_base(4,12,0)
+import Data.Functor.Contravariant
+#endif
+import Data.Functor.Identity
+
+import Control.Applicative
+import Control.Monad
+#if MIN_VERSION_base(4,9,0)
+import qualified Control.Monad.Fail as Fail
+#endif
+import Control.Monad.Fix
+#if MIN_VERSION_base(4,4,0)
+import Control.Monad.Zip (MonadZip(mzipWith))
+#endif
+import Data.Foldable (Foldable(foldMap))
+import Data.Monoid
+import Data.Traversable (Traversable(traverse))
+
+-- | The parameterizable exception monad.
+--
+-- Computations are either exceptions or normal values.
+--
+-- The 'return' function returns a normal value, while @>>=@ exits on
+-- the first exception.  For a variant that continues after an error
+-- and collects all the errors, see 'Control.Applicative.Lift.Errors'.
+type Except e = ExceptT e Identity
+
+-- | Constructor for computations in the exception monad.
+-- (The inverse of 'runExcept').
+except :: (Monad m) => Either e a -> ExceptT e m a
+except m = ExceptT (return m)
+{-# INLINE except #-}
+
+-- | Extractor for computations in the exception monad.
+-- (The inverse of 'except').
+runExcept :: Except e a -> Either e a
+runExcept (ExceptT m) = runIdentity m
+{-# INLINE runExcept #-}
+
+-- | Map the unwrapped computation using the given function.
+--
+-- * @'runExcept' ('mapExcept' f m) = f ('runExcept' m)@
+mapExcept :: (Either e a -> Either e' b)
+        -> Except e a
+        -> Except e' b
+mapExcept f = mapExceptT (Identity . f . runIdentity)
+{-# INLINE mapExcept #-}
+
+-- | Transform any exceptions thrown by the computation using the given
+-- function (a specialization of 'withExceptT').
+withExcept :: (e -> e') -> Except e a -> Except e' a
+withExcept = withExceptT
+{-# INLINE withExcept #-}
+
+-- | A monad transformer that adds exceptions to other monads.
+--
+-- @ExceptT@ constructs a monad parameterized over two things:
+--
+-- * e - The exception type.
+--
+-- * m - The inner monad.
+--
+-- The 'return' function yields a computation that produces the given
+-- value, while @>>=@ sequences two subcomputations, exiting on the
+-- first exception.
+newtype ExceptT e m a = ExceptT (m (Either e a))
+
+instance (Eq e, Eq1 m) => Eq1 (ExceptT e m) where
+    liftEq eq (ExceptT x) (ExceptT y) = liftEq (liftEq eq) x y
+    {-# INLINE liftEq #-}
+
+instance (Ord e, Ord1 m) => Ord1 (ExceptT e m) where
+    liftCompare comp (ExceptT x) (ExceptT y) =
+        liftCompare (liftCompare comp) x y
+    {-# INLINE liftCompare #-}
+
+instance (Read e, Read1 m) => Read1 (ExceptT e m) where
+    liftReadsPrec rp rl = readsData $
+        readsUnaryWith (liftReadsPrec rp' rl') "ExceptT" ExceptT
+      where
+        rp' = liftReadsPrec rp rl
+        rl' = liftReadList rp rl
+
+instance (Show e, Show1 m) => Show1 (ExceptT e m) where
+    liftShowsPrec sp sl d (ExceptT m) =
+        showsUnaryWith (liftShowsPrec sp' sl') "ExceptT" d m
+      where
+        sp' = liftShowsPrec sp sl
+        sl' = liftShowList sp sl
+
+instance (Eq e, Eq1 m, Eq a) => Eq (ExceptT e m a)
+    where (==) = eq1
+instance (Ord e, Ord1 m, Ord a) => Ord (ExceptT e m a)
+    where compare = compare1
+instance (Read e, Read1 m, Read a) => Read (ExceptT e m a) where
+    readsPrec = readsPrec1
+instance (Show e, Show1 m, Show a) => Show (ExceptT e m a) where
+    showsPrec = showsPrec1
+
+-- | The inverse of 'ExceptT'.
+runExceptT :: ExceptT e m a -> m (Either e a)
+runExceptT (ExceptT m) = m
+{-# INLINE runExceptT #-}
+
+-- | Map the unwrapped computation using the given function.
+--
+-- * @'runExceptT' ('mapExceptT' f m) = f ('runExceptT' m)@
+mapExceptT :: (m (Either e a) -> n (Either e' b))
+        -> ExceptT e m a
+        -> ExceptT e' n b
+mapExceptT f m = ExceptT $ f (runExceptT m)
+{-# INLINE mapExceptT #-}
+
+-- | Transform any exceptions thrown by the computation using the
+-- given function.
+withExceptT :: (Functor m) => (e -> e') -> ExceptT e m a -> ExceptT e' m a
+withExceptT f = mapExceptT $ fmap $ either (Left . f) Right
+{-# INLINE withExceptT #-}
+
+instance (Functor m) => Functor (ExceptT e m) where
+    fmap f = ExceptT . fmap (fmap f) . runExceptT
+    {-# INLINE fmap #-}
+
+instance (Foldable f) => Foldable (ExceptT e f) where
+    foldMap f (ExceptT a) = foldMap (either (const mempty) f) a
+    {-# INLINE foldMap #-}
+
+instance (Traversable f) => Traversable (ExceptT e f) where
+    traverse f (ExceptT a) =
+        ExceptT <$> traverse (either (pure . Left) (fmap Right . f)) a
+    {-# INLINE traverse #-}
+
+instance (Functor m, Monad m) => Applicative (ExceptT e m) where
+    pure a = ExceptT $ return (Right a)
+    {-# INLINE pure #-}
+    ExceptT f <*> ExceptT v = ExceptT $ do
+        mf <- f
+        case mf of
+            Left e -> return (Left e)
+            Right k -> do
+                mv <- v
+                case mv of
+                    Left e -> return (Left e)
+                    Right x -> return (Right (k x))
+    {-# INLINEABLE (<*>) #-}
+    m *> k = m >>= \_ -> k
+    {-# INLINE (*>) #-}
+
+instance (Functor m, Monad m, Monoid e) => Alternative (ExceptT e m) where
+    empty = ExceptT $ return (Left mempty)
+    {-# INLINE empty #-}
+    ExceptT mx <|> ExceptT my = ExceptT $ do
+        ex <- mx
+        case ex of
+            Left e -> liftM (either (Left . mappend e) Right) my
+            Right x -> return (Right x)
+    {-# INLINEABLE (<|>) #-}
+
+instance (Monad m) => Monad (ExceptT e m) where
+#if !(MIN_VERSION_base(4,8,0))
+    return a = ExceptT $ return (Right a)
+    {-# INLINE return #-}
+#endif
+    m >>= k = ExceptT $ do
+        a <- runExceptT m
+        case a of
+            Left e -> return (Left e)
+            Right x -> runExceptT (k x)
+    {-# INLINE (>>=) #-}
+#if !(MIN_VERSION_base(4,13,0))
+    fail = ExceptT . fail
+    {-# INLINE fail #-}
+#endif
+
+#if MIN_VERSION_base(4,9,0)
+instance (Fail.MonadFail m) => Fail.MonadFail (ExceptT e m) where
+    fail = ExceptT . Fail.fail
+    {-# INLINE fail #-}
+#endif
+
+instance (Monad m, Monoid e) => MonadPlus (ExceptT e m) where
+    mzero = ExceptT $ return (Left mempty)
+    {-# INLINE mzero #-}
+    ExceptT mx `mplus` ExceptT my = ExceptT $ do
+        ex <- mx
+        case ex of
+            Left e -> liftM (either (Left . mappend e) Right) my
+            Right x -> return (Right x)
+    {-# INLINEABLE mplus #-}
+
+instance (MonadFix m) => MonadFix (ExceptT e m) where
+    mfix f = ExceptT (mfix (runExceptT . f . either (const bomb) id))
+      where bomb = error "mfix (ExceptT): inner computation returned Left value"
+    {-# INLINE mfix #-}
+
+instance MonadTrans (ExceptT e) where
+    lift = ExceptT . liftM Right
+    {-# INLINE lift #-}
+
+instance (MonadIO m) => MonadIO (ExceptT e m) where
+    liftIO = lift . liftIO
+    {-# INLINE liftIO #-}
+
+#if MIN_VERSION_base(4,4,0)
+instance (MonadZip m) => MonadZip (ExceptT e m) where
+    mzipWith f (ExceptT a) (ExceptT b) = ExceptT $ mzipWith (liftA2 f) a b
+    {-# INLINE mzipWith #-}
+#endif
+
+#if MIN_VERSION_base(4,12,0)
+instance Contravariant m => Contravariant (ExceptT e m) where
+    contramap f = ExceptT . contramap (fmap f) . runExceptT
+    {-# INLINE contramap #-}
+#endif
+
+-- | Signal an exception value @e@.
+--
+-- * @'runExceptT' ('throwE' e) = 'return' ('Left' e)@
+--
+-- * @'throwE' e >>= m = 'throwE' e@
+throwE :: (Monad m) => e -> ExceptT e m a
+throwE = ExceptT . return . Left
+{-# INLINE throwE #-}
+
+-- | Handle an exception.
+--
+-- * @'catchE' ('lift' m) h = 'lift' m@
+--
+-- * @'catchE' ('throwE' e) h = h e@
+catchE :: (Monad m) =>
+    ExceptT e m a               -- ^ the inner computation
+    -> (e -> ExceptT e' m a)    -- ^ a handler for exceptions in the inner
+                                -- computation
+    -> ExceptT e' m a
+m `catchE` h = ExceptT $ do
+    a <- runExceptT m
+    case a of
+        Left  l -> runExceptT (h l)
+        Right r -> return (Right r)
+{-# INLINE catchE #-}
+
+-- | Lift a @callCC@ operation to the new monad.
+liftCallCC :: CallCC m (Either e a) (Either e b) -> CallCC (ExceptT e m) a b
+liftCallCC callCC f = ExceptT $
+    callCC $ \ c ->
+    runExceptT (f (\ a -> ExceptT $ c (Right a)))
+{-# INLINE liftCallCC #-}
+
+-- | Lift a @listen@ operation to the new monad.
+liftListen :: (Monad m) => Listen w m (Either e a) -> Listen w (ExceptT e m) a
+liftListen listen = mapExceptT $ \ m -> do
+    (a, w) <- listen m
+    return $! fmap (\ r -> (r, w)) a
+{-# INLINE liftListen #-}
+
+-- | Lift a @pass@ operation to the new monad.
+liftPass :: (Monad m) => Pass w m (Either e a) -> Pass w (ExceptT e m) a
+liftPass pass = mapExceptT $ \ m -> pass $ do
+    a <- m
+    return $! case a of
+        Left l -> (Left l, id)
+        Right (r, f) -> (Right r, f)
+{-# INLINE liftPass #-}

third_party/bazel/rules_haskell/examples/transformers/Control/Monad/Trans/Identity.hs

@@ -0,0 +1,188 @@
+{-# LANGUAGE CPP #-}
+#if __GLASGOW_HASKELL__ >= 702
+{-# LANGUAGE Safe #-}
+#endif
+#if __GLASGOW_HASKELL__ >= 706
+{-# LANGUAGE PolyKinds #-}
+#endif
+#if __GLASGOW_HASKELL__ >= 710
+{-# LANGUAGE AutoDeriveTypeable #-}
+#endif
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Control.Monad.Trans.Identity
+-- Copyright   :  (c) 2007 Magnus Therning
+-- License     :  BSD-style (see the file LICENSE)
+--
+-- Maintainer  :  R.Paterson@city.ac.uk
+-- Stability   :  experimental
+-- Portability :  portable
+--
+-- The identity monad transformer.
+--
+-- This is useful for functions parameterized by a monad transformer.
+-----------------------------------------------------------------------------
+
+module Control.Monad.Trans.Identity (
+    -- * The identity monad transformer
+    IdentityT(..),
+    mapIdentityT,
+    -- * Lifting other operations
+    liftCatch,
+    liftCallCC,
+  ) where
+
+import Control.Monad.IO.Class (MonadIO(liftIO))
+import Control.Monad.Signatures
+import Control.Monad.Trans.Class (MonadTrans(lift))
+import Data.Functor.Classes
+#if MIN_VERSION_base(4,12,0)
+import Data.Functor.Contravariant
+#endif
+
+import Control.Applicative
+import Control.Monad (MonadPlus(mzero, mplus))
+#if MIN_VERSION_base(4,9,0)
+import qualified Control.Monad.Fail as Fail
+#endif
+import Control.Monad.Fix (MonadFix(mfix))
+#if MIN_VERSION_base(4,4,0)
+import Control.Monad.Zip (MonadZip(mzipWith))
+#endif
+import Data.Foldable
+import Data.Traversable (Traversable(traverse))
+import Prelude hiding (foldr, foldr1, foldl, foldl1, null, length)
+
+-- | The trivial monad transformer, which maps a monad to an equivalent monad.
+newtype IdentityT f a = IdentityT { runIdentityT :: f a }
+
+instance (Eq1 f) => Eq1 (IdentityT f) where
+    liftEq eq (IdentityT x) (IdentityT y) = liftEq eq x y
+    {-# INLINE liftEq #-}
+
+instance (Ord1 f) => Ord1 (IdentityT f) where
+    liftCompare comp (IdentityT x) (IdentityT y) = liftCompare comp x y
+    {-# INLINE liftCompare #-}
+
+instance (Read1 f) => Read1 (IdentityT f) where
+    liftReadsPrec rp rl = readsData $
+        readsUnaryWith (liftReadsPrec rp rl) "IdentityT" IdentityT
+
+instance (Show1 f) => Show1 (IdentityT f) where
+    liftShowsPrec sp sl d (IdentityT m) =
+        showsUnaryWith (liftShowsPrec sp sl) "IdentityT" d m
+
+instance (Eq1 f, Eq a) => Eq (IdentityT f a) where (==) = eq1
+instance (Ord1 f, Ord a) => Ord (IdentityT f a) where compare = compare1
+instance (Read1 f, Read a) => Read (IdentityT f a) where readsPrec = readsPrec1
+instance (Show1 f, Show a) => Show (IdentityT f a) where showsPrec = showsPrec1
+
+instance (Functor m) => Functor (IdentityT m) where
+    fmap f = mapIdentityT (fmap f)
+    {-# INLINE fmap #-}
+
+instance (Foldable f) => Foldable (IdentityT f) where
+    foldMap f (IdentityT t) = foldMap f t
+    {-# INLINE foldMap #-}
+    foldr f z (IdentityT t) = foldr f z t
+    {-# INLINE foldr #-}
+    foldl f z (IdentityT t) = foldl f z t
+    {-# INLINE foldl #-}
+    foldr1 f (IdentityT t) = foldr1 f t
+    {-# INLINE foldr1 #-}
+    foldl1 f (IdentityT t) = foldl1 f t
+    {-# INLINE foldl1 #-}
+#if MIN_VERSION_base(4,8,0)
+    null (IdentityT t) = null t
+    length (IdentityT t) = length t
+#endif
+
+instance (Traversable f) => Traversable (IdentityT f) where
+    traverse f (IdentityT a) = IdentityT <$> traverse f a
+    {-# INLINE traverse #-}
+
+instance (Applicative m) => Applicative (IdentityT m) where
+    pure x = IdentityT (pure x)
+    {-# INLINE pure #-}
+    (<*>) = lift2IdentityT (<*>)
+    {-# INLINE (<*>) #-}
+    (*>) = lift2IdentityT (*>)
+    {-# INLINE (*>) #-}
+    (<*) = lift2IdentityT (<*)
+    {-# INLINE (<*) #-}
+
+instance (Alternative m) => Alternative (IdentityT m) where
+    empty = IdentityT empty
+    {-# INLINE empty #-}
+    (<|>) = lift2IdentityT (<|>)
+    {-# INLINE (<|>) #-}
+
+instance (Monad m) => Monad (IdentityT m) where
+#if !(MIN_VERSION_base(4,8,0))
+    return = IdentityT . return
+    {-# INLINE return #-}
+#endif
+    m >>= k = IdentityT $ runIdentityT . k =<< runIdentityT m
+    {-# INLINE (>>=) #-}
+#if !(MIN_VERSION_base(4,13,0))
+    fail msg = IdentityT $ fail msg
+    {-# INLINE fail #-}
+#endif
+
+#if MIN_VERSION_base(4,9,0)
+instance (Fail.MonadFail m) => Fail.MonadFail (IdentityT m) where
+    fail msg = IdentityT $ Fail.fail msg
+    {-# INLINE fail #-}
+#endif
+
+instance (MonadPlus m) => MonadPlus (IdentityT m) where
+    mzero = IdentityT mzero
+    {-# INLINE mzero #-}
+    mplus = lift2IdentityT mplus
+    {-# INLINE mplus #-}
+
+instance (MonadFix m) => MonadFix (IdentityT m) where
+    mfix f = IdentityT (mfix (runIdentityT . f))
+    {-# INLINE mfix #-}
+
+instance (MonadIO m) => MonadIO (IdentityT m) where
+    liftIO = IdentityT . liftIO
+    {-# INLINE liftIO #-}
+
+#if MIN_VERSION_base(4,4,0)
+instance (MonadZip m) => MonadZip (IdentityT m) where
+    mzipWith f = lift2IdentityT (mzipWith f)
+    {-# INLINE mzipWith #-}
+#endif
+
+instance MonadTrans IdentityT where
+    lift = IdentityT
+    {-# INLINE lift #-}
+
+#if MIN_VERSION_base(4,12,0)
+instance Contravariant f => Contravariant (IdentityT f) where
+    contramap f = IdentityT . contramap f . runIdentityT
+    {-# INLINE contramap #-}
+#endif
+
+-- | Lift a unary operation to the new monad.
+mapIdentityT :: (m a -> n b) -> IdentityT m a -> IdentityT n b
+mapIdentityT f = IdentityT . f . runIdentityT
+{-# INLINE mapIdentityT #-}
+
+-- | Lift a binary operation to the new monad.
+lift2IdentityT ::
+    (m a -> n b -> p c) -> IdentityT m a -> IdentityT n b -> IdentityT p c
+lift2IdentityT f a b = IdentityT (f (runIdentityT a) (runIdentityT b))
+{-# INLINE lift2IdentityT #-}
+
+-- | Lift a @callCC@ operation to the new monad.
+liftCallCC :: CallCC m a b -> CallCC (IdentityT m) a b
+liftCallCC callCC f =
+    IdentityT $ callCC $ \ c -> runIdentityT (f (IdentityT . c))
+{-# INLINE liftCallCC #-}
+
+-- | Lift a @catchE@ operation to the new monad.
+liftCatch :: Catch e m a -> Catch e (IdentityT m) a
+liftCatch f m h = IdentityT $ f (runIdentityT m) (runIdentityT . h)
+{-# INLINE liftCatch #-}

third_party/bazel/rules_haskell/examples/transformers/Control/Monad/Trans/List.hs

@@ -0,0 +1,185 @@
+{-# LANGUAGE CPP #-}
+#if __GLASGOW_HASKELL__ >= 702
+{-# LANGUAGE Safe #-}
+#endif
+#if __GLASGOW_HASKELL__ >= 710
+{-# LANGUAGE AutoDeriveTypeable #-}
+#endif
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Control.Monad.Trans.List
+-- Copyright   :  (c) Andy Gill 2001,
+--                (c) Oregon Graduate Institute of Science and Technology, 2001
+-- License     :  BSD-style (see the file LICENSE)
+--
+-- Maintainer  :  R.Paterson@city.ac.uk
+-- Stability   :  experimental
+-- Portability :  portable
+--
+-- The ListT monad transformer, adding backtracking to a given monad,
+-- which must be commutative.
+-----------------------------------------------------------------------------
+
+module Control.Monad.Trans.List
+  {-# DEPRECATED "This transformer is invalid on most monads" #-} (
+    -- * The ListT monad transformer
+    ListT(..),
+    mapListT,
+    -- * Lifting other operations
+    liftCallCC,
+    liftCatch,
+  ) where
+
+import Control.Monad.IO.Class
+import Control.Monad.Signatures
+import Control.Monad.Trans.Class
+import Data.Functor.Classes
+#if MIN_VERSION_base(4,12,0)
+import Data.Functor.Contravariant
+#endif
+
+import Control.Applicative
+import Control.Monad
+#if MIN_VERSION_base(4,9,0)
+import qualified Control.Monad.Fail as Fail
+#endif
+import Control.Monad.Fix
+#if MIN_VERSION_base(4,4,0)
+import Control.Monad.Zip (MonadZip(mzipWith))
+#endif
+import Data.Foldable (Foldable(foldMap))
+import Data.Traversable (Traversable(traverse))
+
+-- | Parameterizable list monad, with an inner monad.
+--
+-- /Note:/ this does not yield a monad unless the argument monad is commutative.
+newtype ListT m a = ListT { runListT :: m [a] }
+
+instance (Eq1 m) => Eq1 (ListT m) where
+    liftEq eq (ListT x) (ListT y) = liftEq (liftEq eq) x y
+    {-# INLINE liftEq #-}
+
+instance (Ord1 m) => Ord1 (ListT m) where
+    liftCompare comp (ListT x) (ListT y) = liftCompare (liftCompare comp) x y
+    {-# INLINE liftCompare #-}
+
+instance (Read1 m) => Read1 (ListT m) where
+    liftReadsPrec rp rl = readsData $
+        readsUnaryWith (liftReadsPrec rp' rl') "ListT" ListT
+      where
+        rp' = liftReadsPrec rp rl
+        rl' = liftReadList rp rl
+
+instance (Show1 m) => Show1 (ListT m) where
+    liftShowsPrec sp sl d (ListT m) =
+        showsUnaryWith (liftShowsPrec sp' sl') "ListT" d m
+      where
+        sp' = liftShowsPrec sp sl
+        sl' = liftShowList sp sl
+
+instance (Eq1 m, Eq a) => Eq (ListT m a) where (==) = eq1
+instance (Ord1 m, Ord a) => Ord (ListT m a) where compare = compare1
+instance (Read1 m, Read a) => Read (ListT m a) where readsPrec = readsPrec1
+instance (Show1 m, Show a) => Show (ListT m a) where showsPrec = showsPrec1
+
+-- | Map between 'ListT' computations.
+--
+-- * @'runListT' ('mapListT' f m) = f ('runListT' m)@
+mapListT :: (m [a] -> n [b]) -> ListT m a -> ListT n b
+mapListT f m = ListT $ f (runListT m)
+{-# INLINE mapListT #-}
+
+instance (Functor m) => Functor (ListT m) where
+    fmap f = mapListT $ fmap $ map f
+    {-# INLINE fmap #-}
+
+instance (Foldable f) => Foldable (ListT f) where
+    foldMap f (ListT a) = foldMap (foldMap f) a
+    {-# INLINE foldMap #-}
+
+instance (Traversable f) => Traversable (ListT f) where
+    traverse f (ListT a) = ListT <$> traverse (traverse f) a
+    {-# INLINE traverse #-}
+
+instance (Applicative m) => Applicative (ListT m) where
+    pure a  = ListT $ pure [a]
+    {-# INLINE pure #-}
+    f <*> v = ListT $ (<*>) <$> runListT f <*> runListT v
+    {-# INLINE (<*>) #-}
+
+instance (Applicative m) => Alternative (ListT m) where
+    empty   = ListT $ pure []
+    {-# INLINE empty #-}
+    m <|> n = ListT $ (++) <$> runListT m <*> runListT n
+    {-# INLINE (<|>) #-}
+
+instance (Monad m) => Monad (ListT m) where
+#if !(MIN_VERSION_base(4,8,0))
+    return a = ListT $ return [a]
+    {-# INLINE return #-}
+#endif
+    m >>= k  = ListT $ do
+        a <- runListT m
+        b <- mapM (runListT . k) a
+        return (concat b)
+    {-# INLINE (>>=) #-}
+#if !(MIN_VERSION_base(4,13,0))
+    fail _ = ListT $ return []
+    {-# INLINE fail #-}
+#endif
+
+#if MIN_VERSION_base(4,9,0)
+instance (Monad m) => Fail.MonadFail (ListT m) where
+    fail _ = ListT $ return []
+    {-# INLINE fail #-}
+#endif
+
+instance (Monad m) => MonadPlus (ListT m) where
+    mzero       = ListT $ return []
+    {-# INLINE mzero #-}
+    m `mplus` n = ListT $ do
+        a <- runListT m
+        b <- runListT n
+        return (a ++ b)
+    {-# INLINE mplus #-}
+
+instance (MonadFix m) => MonadFix (ListT m) where
+    mfix f = ListT $ mfix (runListT . f . head) >>= \ xs -> case xs of
+        [] -> return []
+        x:_ -> liftM (x:) (runListT (mfix (mapListT (liftM tail) . f)))
+    {-# INLINE mfix #-}
+
+instance MonadTrans ListT where
+    lift m = ListT $ do
+        a <- m
+        return [a]
+    {-# INLINE lift #-}
+
+instance (MonadIO m) => MonadIO (ListT m) where
+    liftIO = lift . liftIO
+    {-# INLINE liftIO #-}
+
+#if MIN_VERSION_base(4,4,0)
+instance (MonadZip m) => MonadZip (ListT m) where
+    mzipWith f (ListT a) (ListT b) = ListT $ mzipWith (zipWith f) a b
+    {-# INLINE mzipWith #-}
+#endif
+
+#if MIN_VERSION_base(4,12,0)
+instance Contravariant m => Contravariant (ListT m) where
+    contramap f = ListT . contramap (fmap f) . runListT
+    {-# INLINE contramap #-}
+#endif
+
+-- | Lift a @callCC@ operation to the new monad.
+liftCallCC :: CallCC m [a] [b] -> CallCC (ListT m) a b
+liftCallCC callCC f = ListT $
+    callCC $ \ c ->
+    runListT (f (\ a -> ListT $ c [a]))
+{-# INLINE liftCallCC #-}
+
+-- | Lift a @catchE@ operation to the new monad.
+liftCatch :: Catch e m [a] -> Catch e (ListT m) a
+liftCatch catchE m h = ListT $ runListT m
+    `catchE` \ e -> runListT (h e)
+{-# INLINE liftCatch #-}

third_party/bazel/rules_haskell/examples/transformers/Control/Monad/Trans/Maybe.hs

@@ -0,0 +1,241 @@
+{-# LANGUAGE CPP #-}
+#if __GLASGOW_HASKELL__ >= 702
+{-# LANGUAGE Safe #-}
+#endif
+#if __GLASGOW_HASKELL__ >= 710
+{-# LANGUAGE AutoDeriveTypeable #-}
+#endif
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Control.Monad.Trans.Maybe
+-- Copyright   :  (c) 2007 Yitzak Gale, Eric Kidd
+-- License     :  BSD-style (see the file LICENSE)
+--
+-- Maintainer  :  R.Paterson@city.ac.uk
+-- Stability   :  experimental
+-- Portability :  portable
+--
+-- The 'MaybeT' monad transformer extends a monad with the ability to exit
+-- the computation without returning a value.
+--
+-- A sequence of actions produces a value only if all the actions in
+-- the sequence do.  If one exits, the rest of the sequence is skipped
+-- and the composite action exits.
+--
+-- For a variant allowing a range of exception values, see
+-- "Control.Monad.Trans.Except".
+-----------------------------------------------------------------------------
+
+module Control.Monad.Trans.Maybe (
+    -- * The MaybeT monad transformer
+    MaybeT(..),
+    mapMaybeT,
+    -- * Monad transformations
+    maybeToExceptT,
+    exceptToMaybeT,
+    -- * Lifting other operations
+    liftCallCC,
+    liftCatch,
+    liftListen,
+    liftPass,
+  ) where
+
+import Control.Monad.IO.Class
+import Control.Monad.Signatures
+import Control.Monad.Trans.Class
+import Control.Monad.Trans.Except (ExceptT(..))
+import Data.Functor.Classes
+#if MIN_VERSION_base(4,12,0)
+import Data.Functor.Contravariant
+#endif
+
+import Control.Applicative
+import Control.Monad (MonadPlus(mzero, mplus), liftM)
+#if MIN_VERSION_base(4,9,0)
+import qualified Control.Monad.Fail as Fail
+#endif
+import Control.Monad.Fix (MonadFix(mfix))
+#if MIN_VERSION_base(4,4,0)
+import Control.Monad.Zip (MonadZip(mzipWith))
+#endif
+import Data.Foldable (Foldable(foldMap))
+import Data.Maybe (fromMaybe)
+import Data.Traversable (Traversable(traverse))
+
+-- | The parameterizable maybe monad, obtained by composing an arbitrary
+-- monad with the 'Maybe' monad.
+--
+-- Computations are actions that may produce a value or exit.
+--
+-- The 'return' function yields a computation that produces that
+-- value, while @>>=@ sequences two subcomputations, exiting if either
+-- computation does.
+newtype MaybeT m a = MaybeT { runMaybeT :: m (Maybe a) }
+
+instance (Eq1 m) => Eq1 (MaybeT m) where
+    liftEq eq (MaybeT x) (MaybeT y) = liftEq (liftEq eq) x y
+    {-# INLINE liftEq #-}
+
+instance (Ord1 m) => Ord1 (MaybeT m) where
+    liftCompare comp (MaybeT x) (MaybeT y) = liftCompare (liftCompare comp) x y
+    {-# INLINE liftCompare #-}
+
+instance (Read1 m) => Read1 (MaybeT m) where
+    liftReadsPrec rp rl = readsData $
+        readsUnaryWith (liftReadsPrec rp' rl') "MaybeT" MaybeT
+      where
+        rp' = liftReadsPrec rp rl
+        rl' = liftReadList rp rl
+
+instance (Show1 m) => Show1 (MaybeT m) where
+    liftShowsPrec sp sl d (MaybeT m) =
+        showsUnaryWith (liftShowsPrec sp' sl') "MaybeT" d m
+      where
+        sp' = liftShowsPrec sp sl
+        sl' = liftShowList sp sl
+
+instance (Eq1 m, Eq a) => Eq (MaybeT m a) where (==) = eq1
+instance (Ord1 m, Ord a) => Ord (MaybeT m a) where compare = compare1
+instance (Read1 m, Read a) => Read (MaybeT m a) where readsPrec = readsPrec1
+instance (Show1 m, Show a) => Show (MaybeT m a) where showsPrec = showsPrec1
+
+-- | Transform the computation inside a @MaybeT@.
+--
+-- * @'runMaybeT' ('mapMaybeT' f m) = f ('runMaybeT' m)@
+mapMaybeT :: (m (Maybe a) -> n (Maybe b)) -> MaybeT m a -> MaybeT n b
+mapMaybeT f = MaybeT . f . runMaybeT
+{-# INLINE mapMaybeT #-}
+
+-- | Convert a 'MaybeT' computation to 'ExceptT', with a default
+-- exception value.
+maybeToExceptT :: (Functor m) => e -> MaybeT m a -> ExceptT e m a
+maybeToExceptT e (MaybeT m) = ExceptT $ fmap (maybe (Left e) Right) m
+{-# INLINE maybeToExceptT #-}
+
+-- | Convert a 'ExceptT' computation to 'MaybeT', discarding the
+-- value of any exception.
+exceptToMaybeT :: (Functor m) => ExceptT e m a -> MaybeT m a
+exceptToMaybeT (ExceptT m) = MaybeT $ fmap (either (const Nothing) Just) m
+{-# INLINE exceptToMaybeT #-}
+
+instance (Functor m) => Functor (MaybeT m) where
+    fmap f = mapMaybeT (fmap (fmap f))
+    {-# INLINE fmap #-}
+
+instance (Foldable f) => Foldable (MaybeT f) where
+    foldMap f (MaybeT a) = foldMap (foldMap f) a
+    {-# INLINE foldMap #-}
+
+instance (Traversable f) => Traversable (MaybeT f) where
+    traverse f (MaybeT a) = MaybeT <$> traverse (traverse f) a
+    {-# INLINE traverse #-}
+
+instance (Functor m, Monad m) => Applicative (MaybeT m) where
+    pure = MaybeT . return . Just
+    {-# INLINE pure #-}
+    mf <*> mx = MaybeT $ do
+        mb_f <- runMaybeT mf
+        case mb_f of
+            Nothing -> return Nothing
+            Just f  -> do
+                mb_x <- runMaybeT mx
+                case mb_x of
+                    Nothing -> return Nothing
+                    Just x  -> return (Just (f x))
+    {-# INLINE (<*>) #-}
+    m *> k = m >>= \_ -> k
+    {-# INLINE (*>) #-}
+
+instance (Functor m, Monad m) => Alternative (MaybeT m) where
+    empty = MaybeT (return Nothing)
+    {-# INLINE empty #-}
+    x <|> y = MaybeT $ do
+        v <- runMaybeT x
+        case v of
+            Nothing -> runMaybeT y
+            Just _  -> return v
+    {-# INLINE (<|>) #-}
+
+instance (Monad m) => Monad (MaybeT m) where
+#if !(MIN_VERSION_base(4,8,0))
+    return = MaybeT . return . Just
+    {-# INLINE return #-}
+#endif
+    x >>= f = MaybeT $ do
+        v <- runMaybeT x
+        case v of
+            Nothing -> return Nothing
+            Just y  -> runMaybeT (f y)
+    {-# INLINE (>>=) #-}
+#if !(MIN_VERSION_base(4,13,0))
+    fail _ = MaybeT (return Nothing)
+    {-# INLINE fail #-}
+#endif
+
+#if MIN_VERSION_base(4,9,0)
+instance (Monad m) => Fail.MonadFail (MaybeT m) where
+    fail _ = MaybeT (return Nothing)
+    {-# INLINE fail #-}
+#endif
+
+instance (Monad m) => MonadPlus (MaybeT m) where
+    mzero = MaybeT (return Nothing)
+    {-# INLINE mzero #-}
+    mplus x y = MaybeT $ do
+        v <- runMaybeT x
+        case v of
+            Nothing -> runMaybeT y
+            Just _  -> return v
+    {-# INLINE mplus #-}
+
+instance (MonadFix m) => MonadFix (MaybeT m) where
+    mfix f = MaybeT (mfix (runMaybeT . f . fromMaybe bomb))
+      where bomb = error "mfix (MaybeT): inner computation returned Nothing"
+    {-# INLINE mfix #-}
+
+instance MonadTrans MaybeT where
+    lift = MaybeT . liftM Just
+    {-# INLINE lift #-}
+
+instance (MonadIO m) => MonadIO (MaybeT m) where
+    liftIO = lift . liftIO
+    {-# INLINE liftIO #-}
+
+#if MIN_VERSION_base(4,4,0)
+instance (MonadZip m) => MonadZip (MaybeT m) where
+    mzipWith f (MaybeT a) (MaybeT b) = MaybeT $ mzipWith (liftA2 f) a b
+    {-# INLINE mzipWith #-}
+#endif
+
+#if MIN_VERSION_base(4,12,0)
+instance Contravariant m => Contravariant (MaybeT m) where
+    contramap f = MaybeT . contramap (fmap f) . runMaybeT
+    {-# INLINE contramap #-}
+#endif
+
+-- | Lift a @callCC@ operation to the new monad.
+liftCallCC :: CallCC m (Maybe a) (Maybe b) -> CallCC (MaybeT m) a b
+liftCallCC callCC f =
+    MaybeT $ callCC $ \ c -> runMaybeT (f (MaybeT . c . Just))
+{-# INLINE liftCallCC #-}
+
+-- | Lift a @catchE@ operation to the new monad.
+liftCatch :: Catch e m (Maybe a) -> Catch e (MaybeT m) a
+liftCatch f m h = MaybeT $ f (runMaybeT m) (runMaybeT . h)
+{-# INLINE liftCatch #-}
+
+-- | Lift a @listen@ operation to the new monad.
+liftListen :: (Monad m) => Listen w m (Maybe a) -> Listen w (MaybeT m) a
+liftListen listen = mapMaybeT $ \ m -> do
+    (a, w) <- listen m
+    return $! fmap (\ r -> (r, w)) a
+{-# INLINE liftListen #-}
+
+-- | Lift a @pass@ operation to the new monad.
+liftPass :: (Monad m) => Pass w m (Maybe a) -> Pass w (MaybeT m) a
+liftPass pass = mapMaybeT $ \ m -> pass $ do
+    a <- m
+    return $! case a of
+        Nothing     -> (Nothing, id)
+        Just (v, f) -> (Just v, f)
+{-# INLINE liftPass #-}

third_party/bazel/rules_haskell/examples/transformers/Control/Monad/Trans/RWS.hs

@@ -0,0 +1,25 @@
+{-# LANGUAGE CPP #-}
+#if __GLASGOW_HASKELL__ >= 702
+{-# LANGUAGE Safe #-}
+#endif
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Control.Monad.Trans.RWS
+-- Copyright   :  (c) Andy Gill 2001,
+--                (c) Oregon Graduate Institute of Science and Technology, 2001
+-- License     :  BSD-style (see the file LICENSE)
+--
+-- Maintainer  :  R.Paterson@city.ac.uk
+-- Stability   :  experimental
+-- Portability :  portable
+--
+-- A monad transformer that combines 'ReaderT', 'WriterT' and 'StateT'.
+-- This version is lazy; for a constant-space version with almost the
+-- same interface, see "Control.Monad.Trans.RWS.CPS".
+-----------------------------------------------------------------------------
+
+module Control.Monad.Trans.RWS (
+    module Control.Monad.Trans.RWS.Lazy
+  ) where
+
+import Control.Monad.Trans.RWS.Lazy

third_party/bazel/rules_haskell/examples/transformers/Control/Monad/Trans/RWS/CPS.hs

@@ -0,0 +1,406 @@
+{-# LANGUAGE CPP #-}
+#if __GLASGOW_HASKELL__ >= 702
+{-# LANGUAGE Safe #-}
+#endif
+#if __GLASGOW_HASKELL__ >= 710
+{-# LANGUAGE AutoDeriveTypeable #-}
+#endif
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Control.Monad.Trans.RWS.CPS
+-- Copyright   :  (c) Daniel Mendler 2016,
+--                (c) Andy Gill 2001,
+--                (c) Oregon Graduate Institute of Science and Technology, 2001
+-- License     :  BSD-style (see the file LICENSE)
+--
+-- Maintainer  :  R.Paterson@city.ac.uk
+-- Stability   :  experimental
+-- Portability :  portable
+--
+-- A monad transformer that combines 'ReaderT', 'WriterT' and 'StateT'.
+-- This version uses continuation-passing-style for the writer part
+-- to achieve constant space usage.
+-- For a lazy version with the same interface,
+-- see "Control.Monad.Trans.RWS.Lazy".
+-----------------------------------------------------------------------------
+  
+module Control.Monad.Trans.RWS.CPS (
+    -- * The RWS monad
+    RWS,
+    rws,
+    runRWS,
+    evalRWS,
+    execRWS,
+    mapRWS,
+    withRWS,
+    -- * The RWST monad transformer
+    RWST,
+    rwsT,
+    runRWST,
+    evalRWST,
+    execRWST,
+    mapRWST,
+    withRWST,
+    -- * Reader operations
+    reader,
+    ask,
+    local,
+    asks,
+    -- * Writer operations
+    writer,
+    tell,
+    listen,
+    listens,
+    pass,
+    censor,
+    -- * State operations
+    state,
+    get,
+    put,
+    modify,
+    gets,
+    -- * Lifting other operations
+    liftCallCC,
+    liftCallCC',
+    liftCatch,
+  ) where
+
+import Control.Applicative
+import Control.Monad
+import Control.Monad.Fix
+import Control.Monad.IO.Class
+import Control.Monad.Trans.Class
+import Control.Monad.Signatures
+import Data.Functor.Identity
+
+#if !(MIN_VERSION_base(4,8,0))
+import Data.Monoid
+#endif
+
+#if MIN_VERSION_base(4,9,0)
+import qualified Control.Monad.Fail as Fail
+#endif
+
+-- | A monad containing an environment of type @r@, output of type @w@
+-- and an updatable state of type @s@.
+type RWS r w s = RWST r w s Identity
+
+-- | Construct an RWS computation from a function.
+-- (The inverse of 'runRWS'.)
+rws :: (Monoid w) => (r -> s -> (a, s, w)) -> RWS r w s a
+rws f = RWST $ \ r s w ->
+    let (a, s', w') = f r s; wt = w `mappend` w' in wt `seq` return (a, s', wt)
+{-# INLINE rws #-}
+
+-- | Unwrap an RWS computation as a function.
+-- (The inverse of 'rws'.)
+runRWS :: (Monoid w) => RWS r w s a -> r -> s -> (a, s, w)
+runRWS m r s = runIdentity (runRWST m r s)
+{-# INLINE runRWS #-}
+
+-- | Evaluate a computation with the given initial state and environment,
+-- returning the final value and output, discarding the final state.
+evalRWS :: (Monoid w)
+        => RWS r w s a  -- ^RWS computation to execute
+        -> r            -- ^initial environment
+        -> s            -- ^initial value
+        -> (a, w)       -- ^final value and output
+evalRWS m r s = let
+    (a, _, w) = runRWS m r s
+    in (a, w)
+{-# INLINE evalRWS #-}
+
+-- | Evaluate a computation with the given initial state and environment,
+-- returning the final state and output, discarding the final value.
+execRWS :: (Monoid w)
+        => RWS r w s a  -- ^RWS computation to execute
+        -> r            -- ^initial environment
+        -> s            -- ^initial value
+        -> (s, w)       -- ^final state and output
+execRWS m r s = let
+    (_, s', w) = runRWS m r s
+    in (s', w)
+{-# INLINE execRWS #-}
+
+-- | Map the return value, final state and output of a computation using
+-- the given function.
+--
+-- * @'runRWS' ('mapRWS' f m) r s = f ('runRWS' m r s)@
+mapRWS :: (Monoid w, Monoid w') => ((a, s, w) -> (b, s, w')) -> RWS r w s a -> RWS r w' s b
+mapRWS f = mapRWST (Identity . f . runIdentity)
+{-# INLINE mapRWS #-}
+
+-- | @'withRWS' f m@ executes action @m@ with an initial environment
+-- and state modified by applying @f@.
+--
+-- * @'runRWS' ('withRWS' f m) r s = 'uncurry' ('runRWS' m) (f r s)@
+withRWS :: (r' -> s -> (r, s)) -> RWS r w s a -> RWS r' w s a
+withRWS = withRWST
+{-# INLINE withRWS #-}
+
+-- ---------------------------------------------------------------------------
+-- | A monad transformer adding reading an environment of type @r@,
+-- collecting an output of type @w@ and updating a state of type @s@
+-- to an inner monad @m@.
+newtype RWST r w s m a = RWST { unRWST :: r -> s -> w -> m (a, s, w) }
+
+-- | Construct an RWST computation from a function.
+-- (The inverse of 'runRWST'.)
+rwsT :: (Functor m, Monoid w) => (r -> s -> m (a, s, w)) -> RWST r w s m a
+rwsT f = RWST $ \ r s w ->
+     (\ (a, s', w') -> let wt = w `mappend` w' in wt `seq` (a, s', wt)) <$> f r s
+{-# INLINE rwsT #-}
+
+-- | Unwrap an RWST computation as a function.
+-- (The inverse of 'rwsT'.)
+runRWST :: (Monoid w) => RWST r w s m a -> r -> s -> m (a, s, w)
+runRWST m r s = unRWST m r s mempty
+{-# INLINE runRWST #-}
+
+-- | Evaluate a computation with the given initial state and environment,
+-- returning the final value and output, discarding the final state.
+evalRWST :: (Monad m, Monoid w)
+         => RWST r w s m a      -- ^computation to execute
+         -> r                   -- ^initial environment
+         -> s                   -- ^initial value
+         -> m (a, w)            -- ^computation yielding final value and output
+evalRWST m r s = do
+    (a, _, w) <- runRWST m r s
+    return (a, w)
+{-# INLINE evalRWST #-}
+
+-- | Evaluate a computation with the given initial state and environment,
+-- returning the final state and output, discarding the final value.
+execRWST :: (Monad m, Monoid w)
+         => RWST r w s m a      -- ^computation to execute
+         -> r                   -- ^initial environment
+         -> s                   -- ^initial value
+         -> m (s, w)            -- ^computation yielding final state and output
+execRWST m r s = do
+    (_, s', w) <- runRWST m r s
+    return (s', w)
+{-# INLINE execRWST #-}
+
+-- | Map the inner computation using the given function.
+--
+-- * @'runRWST' ('mapRWST' f m) r s = f ('runRWST' m r s)@
+--mapRWST :: (m (a, s, w) -> n (b, s, w')) -> RWST r w s m a -> RWST r w' s n b
+mapRWST :: (Monad n, Monoid w, Monoid w') =>
+    (m (a, s, w) -> n (b, s, w')) -> RWST r w s m a -> RWST r w' s n b
+mapRWST f m = RWST $ \ r s w -> do
+    (a, s', w') <- f (runRWST m r s)
+    let wt = w `mappend` w'
+    wt `seq` return (a, s', wt)
+{-# INLINE mapRWST #-}
+
+-- | @'withRWST' f m@ executes action @m@ with an initial environment
+-- and state modified by applying @f@.
+--
+-- * @'runRWST' ('withRWST' f m) r s = 'uncurry' ('runRWST' m) (f r s)@
+withRWST :: (r' -> s -> (r, s)) -> RWST r w s m a -> RWST r' w s m a
+withRWST f m = RWST $ \ r s -> uncurry (unRWST m) (f r s)
+{-# INLINE withRWST #-}
+
+instance (Functor m) => Functor (RWST r w s m) where
+    fmap f m = RWST $ \ r s w -> (\ (a, s', w') -> (f a, s', w')) <$> unRWST m r s w
+    {-# INLINE fmap #-}
+
+instance (Functor m, Monad m) => Applicative (RWST r w s m) where
+    pure a = RWST $ \ _ s w -> return (a, s, w)
+    {-# INLINE pure #-}
+
+    RWST mf <*> RWST mx = RWST $ \ r s w -> do
+        (f, s', w')    <- mf r s w
+        (x, s'', w'') <- mx r s' w'
+        return (f x, s'', w'')
+    {-# INLINE (<*>) #-}
+
+instance (Functor m, MonadPlus m) => Alternative (RWST r w s m) where
+    empty = RWST $ \ _ _ _ -> mzero
+    {-# INLINE empty #-}
+
+    RWST m <|> RWST n = RWST $ \ r s w -> m r s w `mplus` n r s w
+    {-# INLINE (<|>) #-}
+
+instance (Monad m) => Monad (RWST r w s m) where
+#if !(MIN_VERSION_base(4,8,0))
+    return a = RWST $ \ _ s w -> return (a, s, w)
+    {-# INLINE return #-}
+#endif
+
+    m >>= k = RWST $ \ r s w -> do
+        (a, s', w')    <- unRWST m r s w
+        unRWST (k a) r s' w'
+    {-# INLINE (>>=) #-}
+
+#if !(MIN_VERSION_base(4,13,0))
+    fail msg = RWST $ \ _ _ _ -> fail msg
+    {-# INLINE fail #-}
+#endif
+
+#if MIN_VERSION_base(4,9,0)
+instance (Fail.MonadFail m) => Fail.MonadFail (RWST r w s m) where
+    fail msg = RWST $ \ _ _ _ -> Fail.fail msg
+    {-# INLINE fail #-}
+#endif
+
+instance (Functor m, MonadPlus m) => MonadPlus (RWST r w s m) where
+    mzero = empty
+    {-# INLINE mzero #-}
+    mplus = (<|>)
+    {-# INLINE mplus #-}
+
+instance (MonadFix m) => MonadFix (RWST r w s m) where
+    mfix f = RWST $ \ r s w -> mfix $ \ ~(a, _, _) -> unRWST (f a) r s w
+    {-# INLINE mfix #-}
+
+instance MonadTrans (RWST r w s) where
+    lift m = RWST $ \ _ s w -> do
+        a <- m
+        return (a, s, w)
+    {-# INLINE lift #-}
+
+instance (MonadIO m) => MonadIO (RWST r w s m) where
+    liftIO = lift . liftIO
+    {-# INLINE liftIO #-}
+-- ---------------------------------------------------------------------------
+-- Reader operations
+
+-- | Constructor for computations in the reader monad (equivalent to 'asks').
+reader :: (Monad m) => (r -> a) -> RWST r w s m a
+reader = asks
+{-# INLINE reader #-}
+
+-- | Fetch the value of the environment.
+ask :: (Monad m) => RWST r w s m r
+ask = asks id
+{-# INLINE ask #-}
+
+-- | Execute a computation in a modified environment
+--
+-- * @'runRWST' ('local' f m) r s = 'runRWST' m (f r) s@
+local :: (r -> r) -> RWST r w s m a -> RWST r w s m a
+local f m = RWST $ \ r s w -> unRWST m (f r) s w
+{-# INLINE local #-}
+
+-- | Retrieve a function of the current environment.
+--
+-- * @'asks' f = 'liftM' f 'ask'@
+asks :: (Monad m) => (r -> a) -> RWST r w s m a
+asks f = RWST $ \ r s w -> return (f r, s, w)
+{-# INLINE asks #-}
+
+-- ---------------------------------------------------------------------------
+-- Writer operations
+
+-- | Construct a writer computation from a (result, output) pair.
+writer :: (Monoid w, Monad m) => (a, w) -> RWST r w s m a
+writer (a, w') = RWST $ \ _ s w -> let wt = w `mappend` w' in wt `seq` return (a, s, wt)
+{-# INLINE writer #-}
+
+-- | @'tell' w@ is an action that produces the output @w@.
+tell :: (Monoid w, Monad m) => w -> RWST r w s m ()
+tell w' = writer ((), w')
+{-# INLINE tell #-}
+
+-- | @'listen' m@ is an action that executes the action @m@ and adds its
+-- output to the value of the computation.
+--
+-- * @'runRWST' ('listen' m) r s = 'liftM' (\\ (a, w) -> ((a, w), w)) ('runRWST' m r s)@
+listen :: (Monoid w, Monad m) => RWST r w s m a -> RWST r w s m (a, w)
+listen = listens id
+{-# INLINE listen #-}
+
+-- | @'listens' f m@ is an action that executes the action @m@ and adds
+-- the result of applying @f@ to the output to the value of the computation.
+--
+-- * @'listens' f m = 'liftM' (id *** f) ('listen' m)@
+--
+-- * @'runRWST' ('listens' f m) r s = 'liftM' (\\ (a, w) -> ((a, f w), w)) ('runRWST' m r s)@
+listens :: (Monoid w, Monad m) => (w -> b) -> RWST r w s m a -> RWST r w s m (a, b)
+listens f m = RWST $ \ r s w -> do
+    (a, s', w') <- runRWST m r s
+    let wt = w `mappend` w'
+    wt `seq` return ((a, f w'), s', wt)
+{-# INLINE listens #-}
+
+-- | @'pass' m@ is an action that executes the action @m@, which returns
+-- a value and a function, and returns the value, applying the function
+-- to the output.
+--
+-- * @'runRWST' ('pass' m) r s = 'liftM' (\\ ((a, f), w) -> (a, f w)) ('runRWST' m r s)@
+pass :: (Monoid w, Monoid w', Monad m) => RWST r w s m (a, w -> w') -> RWST r w' s m a
+pass m = RWST $ \ r s w -> do
+    ((a, f), s', w') <- runRWST m r s
+    let wt = w `mappend` f w'
+    wt `seq` return (a, s', wt)
+{-# INLINE pass #-}
+
+-- | @'censor' f m@ is an action that executes the action @m@ and
+-- applies the function @f@ to its output, leaving the return value
+-- unchanged.
+--
+-- * @'censor' f m = 'pass' ('liftM' (\\ x -> (x,f)) m)@
+--
+-- * @'runRWST' ('censor' f m) r s = 'liftM' (\\ (a, w) -> (a, f w)) ('runRWST' m r s)@
+censor :: (Monoid w, Monad m) => (w -> w) -> RWST r w s m a -> RWST r w s m a
+censor f m = RWST $ \ r s w -> do
+    (a, s', w') <- runRWST m r s
+    let wt = w `mappend` f w'
+    wt `seq` return (a, s', wt)
+{-# INLINE censor #-}
+
+-- ---------------------------------------------------------------------------
+-- State operations
+
+-- | Construct a state monad computation from a state transformer function.
+state :: (Monad m) => (s -> (a, s)) -> RWST r w s m a
+state f = RWST $ \ _ s w -> let (a, s') = f s in return (a, s', w)
+{-# INLINE state #-}
+
+-- | Fetch the current value of the state within the monad.
+get :: (Monad m) =>RWST r w s m s
+get = gets id
+{-# INLINE get #-}
+
+-- | @'put' s@ sets the state within the monad to @s@.
+put :: (Monad m) =>s -> RWST r w s m ()
+put s = RWST $ \ _ _ w -> return ((), s, w)
+{-# INLINE put #-}
+
+-- | @'modify' f@ is an action that updates the state to the result of
+-- applying @f@ to the current state.
+--
+-- * @'modify' f = 'get' >>= ('put' . f)@
+modify :: (Monad m) =>(s -> s) -> RWST r w s m ()
+modify f = RWST $ \ _ s w -> return ((), f s, w)
+{-# INLINE modify #-}
+
+-- | Get a specific component of the state, using a projection function
+-- supplied.
+--
+-- * @'gets' f = 'liftM' f 'get'@
+gets :: (Monad m) =>(s -> a) -> RWST r w s m a
+gets f = RWST $ \ _ s w -> return (f s, s, w)
+{-# INLINE gets #-}
+
+-- | Uniform lifting of a @callCC@ operation to the new monad.
+-- This version rolls back to the original state on entering the
+-- continuation.
+liftCallCC :: CallCC m (a,s,w) (b,s,w) -> CallCC (RWST r w s m) a b
+liftCallCC callCC f = RWST $ \ r s w ->
+    callCC $ \ c -> unRWST (f (\ a -> RWST $ \ _ _ _ -> c (a, s, w))) r s w
+{-# INLINE liftCallCC #-}
+
+-- | In-situ lifting of a @callCC@ operation to the new monad.
+-- This version uses the current state on entering the continuation.
+liftCallCC' :: CallCC m (a,s,w) (b,s,w) -> CallCC (RWST r w s m) a b
+liftCallCC' callCC f = RWST $ \ r s w ->
+    callCC $ \ c -> unRWST (f (\ a -> RWST $ \ _ s' _ -> c (a, s', w))) r s w
+{-# INLINE liftCallCC' #-}
+
+-- | Lift a @catchE@ operation to the new monad.
+liftCatch :: Catch e m (a,s,w) -> Catch e (RWST r w s m) a
+liftCatch catchE m h =
+    RWST $ \ r s w -> unRWST m r s w `catchE` \ e -> unRWST (h e) r s w
+{-# INLINE liftCatch #-}

third_party/bazel/rules_haskell/examples/transformers/Control/Monad/Trans/RWS/Lazy.hs

@@ -0,0 +1,389 @@
+{-# LANGUAGE CPP #-}
+#if __GLASGOW_HASKELL__ >= 702
+{-# LANGUAGE Safe #-}
+#endif
+#if __GLASGOW_HASKELL__ >= 710
+{-# LANGUAGE AutoDeriveTypeable #-}
+#endif
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Control.Monad.Trans.RWS.Lazy
+-- Copyright   :  (c) Andy Gill 2001,
+--                (c) Oregon Graduate Institute of Science and Technology, 2001
+-- License     :  BSD-style (see the file LICENSE)
+--
+-- Maintainer  :  R.Paterson@city.ac.uk
+-- Stability   :  experimental
+-- Portability :  portable
+--
+-- A monad transformer that combines 'ReaderT', 'WriterT' and 'StateT'.
+-- This version is lazy; for a constant-space version with almost the
+-- same interface, see "Control.Monad.Trans.RWS.CPS".
+-----------------------------------------------------------------------------
+
+module Control.Monad.Trans.RWS.Lazy (
+    -- * The RWS monad
+    RWS,
+    rws,
+    runRWS,
+    evalRWS,
+    execRWS,
+    mapRWS,
+    withRWS,
+    -- * The RWST monad transformer
+    RWST(..),
+    evalRWST,
+    execRWST,
+    mapRWST,
+    withRWST,
+    -- * Reader operations
+    reader,
+    ask,
+    local,
+    asks,
+    -- * Writer operations
+    writer,
+    tell,
+    listen,
+    listens,
+    pass,
+    censor,
+    -- * State operations
+    state,
+    get,
+    put,
+    modify,
+    gets,
+    -- * Lifting other operations
+    liftCallCC,
+    liftCallCC',
+    liftCatch,
+  ) where
+
+import Control.Monad.IO.Class
+import Control.Monad.Signatures
+import Control.Monad.Trans.Class
+#if MIN_VERSION_base(4,12,0)
+import Data.Functor.Contravariant
+#endif
+import Data.Functor.Identity
+
+import Control.Applicative
+import Control.Monad
+#if MIN_VERSION_base(4,9,0)
+import qualified Control.Monad.Fail as Fail
+#endif
+import Control.Monad.Fix
+import Data.Monoid
+
+-- | A monad containing an environment of type @r@, output of type @w@
+-- and an updatable state of type @s@.
+type RWS r w s = RWST r w s Identity
+
+-- | Construct an RWS computation from a function.
+-- (The inverse of 'runRWS'.)
+rws :: (r -> s -> (a, s, w)) -> RWS r w s a
+rws f = RWST (\ r s -> Identity (f r s))
+{-# INLINE rws #-}
+
+-- | Unwrap an RWS computation as a function.
+-- (The inverse of 'rws'.)
+runRWS :: RWS r w s a -> r -> s -> (a, s, w)
+runRWS m r s = runIdentity (runRWST m r s)
+{-# INLINE runRWS #-}
+
+-- | Evaluate a computation with the given initial state and environment,
+-- returning the final value and output, discarding the final state.
+evalRWS :: RWS r w s a  -- ^RWS computation to execute
+        -> r            -- ^initial environment
+        -> s            -- ^initial value
+        -> (a, w)       -- ^final value and output
+evalRWS m r s = let
+    (a, _, w) = runRWS m r s
+    in (a, w)
+{-# INLINE evalRWS #-}
+
+-- | Evaluate a computation with the given initial state and environment,
+-- returning the final state and output, discarding the final value.
+execRWS :: RWS r w s a  -- ^RWS computation to execute
+        -> r            -- ^initial environment
+        -> s            -- ^initial value
+        -> (s, w)       -- ^final state and output
+execRWS m r s = let
+    (_, s', w) = runRWS m r s
+    in (s', w)
+{-# INLINE execRWS #-}
+
+-- | Map the return value, final state and output of a computation using
+-- the given function.
+--
+-- * @'runRWS' ('mapRWS' f m) r s = f ('runRWS' m r s)@
+mapRWS :: ((a, s, w) -> (b, s, w')) -> RWS r w s a -> RWS r w' s b
+mapRWS f = mapRWST (Identity . f . runIdentity)
+{-# INLINE mapRWS #-}
+
+-- | @'withRWS' f m@ executes action @m@ with an initial environment
+-- and state modified by applying @f@.
+--
+-- * @'runRWS' ('withRWS' f m) r s = 'uncurry' ('runRWS' m) (f r s)@
+withRWS :: (r' -> s -> (r, s)) -> RWS r w s a -> RWS r' w s a
+withRWS = withRWST
+{-# INLINE withRWS #-}
+
+-- ---------------------------------------------------------------------------
+-- | A monad transformer adding reading an environment of type @r@,
+-- collecting an output of type @w@ and updating a state of type @s@
+-- to an inner monad @m@.
+newtype RWST r w s m a = RWST { runRWST :: r -> s -> m (a, s, w) }
+
+-- | Evaluate a computation with the given initial state and environment,
+-- returning the final value and output, discarding the final state.
+evalRWST :: (Monad m)
+         => RWST r w s m a      -- ^computation to execute
+         -> r                   -- ^initial environment
+         -> s                   -- ^initial value
+         -> m (a, w)            -- ^computation yielding final value and output
+evalRWST m r s = do
+    ~(a, _, w) <- runRWST m r s
+    return (a, w)
+{-# INLINE evalRWST #-}
+
+-- | Evaluate a computation with the given initial state and environment,
+-- returning the final state and output, discarding the final value.
+execRWST :: (Monad m)
+         => RWST r w s m a      -- ^computation to execute
+         -> r                   -- ^initial environment
+         -> s                   -- ^initial value
+         -> m (s, w)            -- ^computation yielding final state and output
+execRWST m r s = do
+    ~(_, s', w) <- runRWST m r s
+    return (s', w)
+{-# INLINE execRWST #-}
+
+-- | Map the inner computation using the given function.
+--
+-- * @'runRWST' ('mapRWST' f m) r s = f ('runRWST' m r s)@
+mapRWST :: (m (a, s, w) -> n (b, s, w')) -> RWST r w s m a -> RWST r w' s n b
+mapRWST f m = RWST $ \ r s -> f (runRWST m r s)
+{-# INLINE mapRWST #-}
+
+-- | @'withRWST' f m@ executes action @m@ with an initial environment
+-- and state modified by applying @f@.
+--
+-- * @'runRWST' ('withRWST' f m) r s = 'uncurry' ('runRWST' m) (f r s)@
+withRWST :: (r' -> s -> (r, s)) -> RWST r w s m a -> RWST r' w s m a
+withRWST f m = RWST $ \ r s -> uncurry (runRWST m) (f r s)
+{-# INLINE withRWST #-}
+
+instance (Functor m) => Functor (RWST r w s m) where
+    fmap f m = RWST $ \ r s ->
+        fmap (\ ~(a, s', w) -> (f a, s', w)) $ runRWST m r s
+    {-# INLINE fmap #-}
+
+instance (Monoid w, Functor m, Monad m) => Applicative (RWST r w s m) where
+    pure a = RWST $ \ _ s -> return (a, s, mempty)
+    {-# INLINE pure #-}
+    RWST mf <*> RWST mx  = RWST $ \ r s -> do
+        ~(f, s', w)  <- mf r s
+        ~(x, s'',w') <- mx r s'
+        return (f x, s'', w `mappend` w')
+    {-# INLINE (<*>) #-}
+
+instance (Monoid w, Functor m, MonadPlus m) => Alternative (RWST r w s m) where
+    empty = RWST $ \ _ _ -> mzero
+    {-# INLINE empty #-}
+    RWST m <|> RWST n = RWST $ \ r s -> m r s `mplus` n r s
+    {-# INLINE (<|>) #-}
+
+instance (Monoid w, Monad m) => Monad (RWST r w s m) where
+#if !(MIN_VERSION_base(4,8,0))
+    return a = RWST $ \ _ s -> return (a, s, mempty)
+    {-# INLINE return #-}
+#endif
+    m >>= k  = RWST $ \ r s -> do
+        ~(a, s', w)  <- runRWST m r s
+        ~(b, s'',w') <- runRWST (k a) r s'
+        return (b, s'', w `mappend` w')
+    {-# INLINE (>>=) #-}
+#if !(MIN_VERSION_base(4,13,0))
+    fail msg = RWST $ \ _ _ -> fail msg
+    {-# INLINE fail #-}
+#endif
+
+#if MIN_VERSION_base(4,9,0)
+instance (Monoid w, Fail.MonadFail m) => Fail.MonadFail (RWST r w s m) where
+    fail msg = RWST $ \ _ _ -> Fail.fail msg
+    {-# INLINE fail #-}
+#endif
+
+instance (Monoid w, MonadPlus m) => MonadPlus (RWST r w s m) where
+    mzero = RWST $ \ _ _ -> mzero
+    {-# INLINE mzero #-}
+    RWST m `mplus` RWST n = RWST $ \ r s -> m r s `mplus` n r s
+    {-# INLINE mplus #-}
+
+instance (Monoid w, MonadFix m) => MonadFix (RWST r w s m) where
+    mfix f = RWST $ \ r s -> mfix $ \ ~(a, _, _) -> runRWST (f a) r s
+    {-# INLINE mfix #-}
+
+instance (Monoid w) => MonadTrans (RWST r w s) where
+    lift m = RWST $ \ _ s -> do
+        a <- m
+        return (a, s, mempty)
+    {-# INLINE lift #-}
+
+instance (Monoid w, MonadIO m) => MonadIO (RWST r w s m) where
+    liftIO = lift . liftIO
+    {-# INLINE liftIO #-}
+
+#if MIN_VERSION_base(4,12,0)
+instance Contravariant m => Contravariant (RWST r w s m) where
+    contramap f m = RWST $ \r s ->
+      contramap (\ ~(a, s', w) -> (f a, s', w)) $ runRWST m r s
+    {-# INLINE contramap #-}
+#endif
+
+-- ---------------------------------------------------------------------------
+-- Reader operations
+
+-- | Constructor for computations in the reader monad (equivalent to 'asks').
+reader :: (Monoid w, Monad m) => (r -> a) -> RWST r w s m a
+reader = asks
+{-# INLINE reader #-}
+
+-- | Fetch the value of the environment.
+ask :: (Monoid w, Monad m) => RWST r w s m r
+ask = RWST $ \ r s -> return (r, s, mempty)
+{-# INLINE ask #-}
+
+-- | Execute a computation in a modified environment
+--
+-- * @'runRWST' ('local' f m) r s = 'runRWST' m (f r) s@
+local :: (r -> r) -> RWST r w s m a -> RWST r w s m a
+local f m = RWST $ \ r s -> runRWST m (f r) s
+{-# INLINE local #-}
+
+-- | Retrieve a function of the current environment.
+--
+-- * @'asks' f = 'liftM' f 'ask'@
+asks :: (Monoid w, Monad m) => (r -> a) -> RWST r w s m a
+asks f = RWST $ \ r s -> return (f r, s, mempty)
+{-# INLINE asks #-}
+
+-- ---------------------------------------------------------------------------
+-- Writer operations
+
+-- | Construct a writer computation from a (result, output) pair.
+writer :: (Monad m) => (a, w) -> RWST r w s m a
+writer (a, w) = RWST $ \ _ s -> return (a, s, w)
+{-# INLINE writer #-}
+
+-- | @'tell' w@ is an action that produces the output @w@.
+tell :: (Monad m) => w -> RWST r w s m ()
+tell w = RWST $ \ _ s -> return ((),s,w)
+{-# INLINE tell #-}
+
+-- | @'listen' m@ is an action that executes the action @m@ and adds its
+-- output to the value of the computation.
+--
+-- * @'runRWST' ('listen' m) r s = 'liftM' (\\ (a, w) -> ((a, w), w)) ('runRWST' m r s)@
+listen :: (Monad m) => RWST r w s m a -> RWST r w s m (a, w)
+listen m = RWST $ \ r s -> do
+    ~(a, s', w) <- runRWST m r s
+    return ((a, w), s', w)
+{-# INLINE listen #-}
+
+-- | @'listens' f m@ is an action that executes the action @m@ and adds
+-- the result of applying @f@ to the output to the value of the computation.
+--
+-- * @'listens' f m = 'liftM' (id *** f) ('listen' m)@
+--
+-- * @'runRWST' ('listens' f m) r s = 'liftM' (\\ (a, w) -> ((a, f w), w)) ('runRWST' m r s)@
+listens :: (Monad m) => (w -> b) -> RWST r w s m a -> RWST r w s m (a, b)
+listens f m = RWST $ \ r s -> do
+    ~(a, s', w) <- runRWST m r s
+    return ((a, f w), s', w)
+{-# INLINE listens #-}
+
+-- | @'pass' m@ is an action that executes the action @m@, which returns
+-- a value and a function, and returns the value, applying the function
+-- to the output.
+--
+-- * @'runRWST' ('pass' m) r s = 'liftM' (\\ ((a, f), w) -> (a, f w)) ('runRWST' m r s)@
+pass :: (Monad m) => RWST r w s m (a, w -> w) -> RWST r w s m a
+pass m = RWST $ \ r s -> do
+    ~((a, f), s', w) <- runRWST m r s
+    return (a, s', f w)
+{-# INLINE pass #-}
+
+-- | @'censor' f m@ is an action that executes the action @m@ and
+-- applies the function @f@ to its output, leaving the return value
+-- unchanged.
+--
+-- * @'censor' f m = 'pass' ('liftM' (\\ x -> (x,f)) m)@
+--
+-- * @'runRWST' ('censor' f m) r s = 'liftM' (\\ (a, w) -> (a, f w)) ('runRWST' m r s)@
+censor :: (Monad m) => (w -> w) -> RWST r w s m a -> RWST r w s m a
+censor f m = RWST $ \ r s -> do
+    ~(a, s', w) <- runRWST m r s
+    return (a, s', f w)
+{-# INLINE censor #-}
+
+-- ---------------------------------------------------------------------------
+-- State operations
+
+-- | Construct a state monad computation from a state transformer function.
+state :: (Monoid w, Monad m) => (s -> (a,s)) -> RWST r w s m a
+state f = RWST $ \ _ s -> let (a,s') = f s  in  return (a, s', mempty)
+{-# INLINE state #-}
+
+-- | Fetch the current value of the state within the monad.
+get :: (Monoid w, Monad m) => RWST r w s m s
+get = RWST $ \ _ s -> return (s, s, mempty)
+{-# INLINE get #-}
+
+-- | @'put' s@ sets the state within the monad to @s@.
+put :: (Monoid w, Monad m) => s -> RWST r w s m ()
+put s = RWST $ \ _ _ -> return ((), s, mempty)
+{-# INLINE put #-}
+
+-- | @'modify' f@ is an action that updates the state to the result of
+-- applying @f@ to the current state.
+--
+-- * @'modify' f = 'get' >>= ('put' . f)@
+modify :: (Monoid w, Monad m) => (s -> s) -> RWST r w s m ()
+modify f = RWST $ \ _ s -> return ((), f s, mempty)
+{-# INLINE modify #-}
+
+-- | Get a specific component of the state, using a projection function
+-- supplied.
+--
+-- * @'gets' f = 'liftM' f 'get'@
+gets :: (Monoid w, Monad m) => (s -> a) -> RWST r w s m a
+gets f = RWST $ \ _ s -> return (f s, s, mempty)
+{-# INLINE gets #-}
+
+-- | Uniform lifting of a @callCC@ operation to the new monad.
+-- This version rolls back to the original state on entering the
+-- continuation.
+liftCallCC :: (Monoid w) =>
+    CallCC m (a,s,w) (b,s,w) -> CallCC (RWST r w s m) a b
+liftCallCC callCC f = RWST $ \ r s ->
+    callCC $ \ c ->
+    runRWST (f (\ a -> RWST $ \ _ _ -> c (a, s, mempty))) r s
+{-# INLINE liftCallCC #-}
+
+-- | In-situ lifting of a @callCC@ operation to the new monad.
+-- This version uses the current state on entering the continuation.
+liftCallCC' :: (Monoid w) =>
+    CallCC m (a,s,w) (b,s,w) -> CallCC (RWST r w s m) a b
+liftCallCC' callCC f = RWST $ \ r s ->
+    callCC $ \ c ->
+    runRWST (f (\ a -> RWST $ \ _ s' -> c (a, s', mempty))) r s
+{-# INLINE liftCallCC' #-}
+
+-- | Lift a @catchE@ operation to the new monad.
+liftCatch :: Catch e m (a,s,w) -> Catch e (RWST r w s m) a
+liftCatch catchE m h =
+    RWST $ \ r s -> runRWST m r s `catchE` \ e -> runRWST (h e) r s
+{-# INLINE liftCatch #-}

third_party/bazel/rules_haskell/examples/transformers/Control/Monad/Trans/RWS/Strict.hs

@@ -0,0 +1,392 @@
+{-# LANGUAGE CPP #-}
+#if __GLASGOW_HASKELL__ >= 702
+{-# LANGUAGE Safe #-}
+#endif
+#if __GLASGOW_HASKELL__ >= 710
+{-# LANGUAGE AutoDeriveTypeable #-}
+#endif
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Control.Monad.Trans.RWS.Strict
+-- Copyright   :  (c) Andy Gill 2001,
+--                (c) Oregon Graduate Institute of Science and Technology, 2001
+-- License     :  BSD-style (see the file LICENSE)
+--
+-- Maintainer  :  R.Paterson@city.ac.uk
+-- Stability   :  experimental
+-- Portability :  portable
+--
+-- A monad transformer that combines 'ReaderT', 'WriterT' and 'StateT'.
+-- This version is strict; for a lazy version with the same interface,
+-- see "Control.Monad.Trans.RWS.Lazy".
+-- Although the output is built strictly, it is not possible to
+-- achieve constant space behaviour with this transformer: for that,
+-- use "Control.Monad.Trans.RWS.CPS" instead.
+-----------------------------------------------------------------------------
+
+module Control.Monad.Trans.RWS.Strict (
+    -- * The RWS monad
+    RWS,
+    rws,
+    runRWS,
+    evalRWS,
+    execRWS,
+    mapRWS,
+    withRWS,
+    -- * The RWST monad transformer
+    RWST(..),
+    evalRWST,
+    execRWST,
+    mapRWST,
+    withRWST,
+    -- * Reader operations
+    reader,
+    ask,
+    local,
+    asks,
+    -- * Writer operations
+    writer,
+    tell,
+    listen,
+    listens,
+    pass,
+    censor,
+    -- * State operations
+    state,
+    get,
+    put,
+    modify,
+    gets,
+    -- * Lifting other operations
+    liftCallCC,
+    liftCallCC',
+    liftCatch,
+  ) where
+
+import Control.Monad.IO.Class
+import Control.Monad.Signatures
+import Control.Monad.Trans.Class
+#if MIN_VERSION_base(4,12,0)
+import Data.Functor.Contravariant
+#endif
+import Data.Functor.Identity
+
+import Control.Applicative
+import Control.Monad
+#if MIN_VERSION_base(4,9,0)
+import qualified Control.Monad.Fail as Fail
+#endif
+import Control.Monad.Fix
+import Data.Monoid
+
+-- | A monad containing an environment of type @r@, output of type @w@
+-- and an updatable state of type @s@.
+type RWS r w s = RWST r w s Identity
+
+-- | Construct an RWS computation from a function.
+-- (The inverse of 'runRWS'.)
+rws :: (r -> s -> (a, s, w)) -> RWS r w s a
+rws f = RWST (\ r s -> Identity (f r s))
+{-# INLINE rws #-}
+
+-- | Unwrap an RWS computation as a function.
+-- (The inverse of 'rws'.)
+runRWS :: RWS r w s a -> r -> s -> (a, s, w)
+runRWS m r s = runIdentity (runRWST m r s)
+{-# INLINE runRWS #-}
+
+-- | Evaluate a computation with the given initial state and environment,
+-- returning the final value and output, discarding the final state.
+evalRWS :: RWS r w s a  -- ^RWS computation to execute
+        -> r            -- ^initial environment
+        -> s            -- ^initial value
+        -> (a, w)       -- ^final value and output
+evalRWS m r s = let
+    (a, _, w) = runRWS m r s
+    in (a, w)
+{-# INLINE evalRWS #-}
+
+-- | Evaluate a computation with the given initial state and environment,
+-- returning the final state and output, discarding the final value.
+execRWS :: RWS r w s a  -- ^RWS computation to execute
+        -> r            -- ^initial environment
+        -> s            -- ^initial value
+        -> (s, w)       -- ^final state and output
+execRWS m r s = let
+    (_, s', w) = runRWS m r s
+    in (s', w)
+{-# INLINE execRWS #-}
+
+-- | Map the return value, final state and output of a computation using
+-- the given function.
+--
+-- * @'runRWS' ('mapRWS' f m) r s = f ('runRWS' m r s)@
+mapRWS :: ((a, s, w) -> (b, s, w')) -> RWS r w s a -> RWS r w' s b
+mapRWS f = mapRWST (Identity . f . runIdentity)
+{-# INLINE mapRWS #-}
+
+-- | @'withRWS' f m@ executes action @m@ with an initial environment
+-- and state modified by applying @f@.
+--
+-- * @'runRWS' ('withRWS' f m) r s = 'uncurry' ('runRWS' m) (f r s)@
+withRWS :: (r' -> s -> (r, s)) -> RWS r w s a -> RWS r' w s a
+withRWS = withRWST
+{-# INLINE withRWS #-}
+
+-- ---------------------------------------------------------------------------
+-- | A monad transformer adding reading an environment of type @r@,
+-- collecting an output of type @w@ and updating a state of type @s@
+-- to an inner monad @m@.
+newtype RWST r w s m a = RWST { runRWST :: r -> s -> m (a, s, w) }
+
+-- | Evaluate a computation with the given initial state and environment,
+-- returning the final value and output, discarding the final state.
+evalRWST :: (Monad m)
+         => RWST r w s m a      -- ^computation to execute
+         -> r                   -- ^initial environment
+         -> s                   -- ^initial value
+         -> m (a, w)            -- ^computation yielding final value and output
+evalRWST m r s = do
+    (a, _, w) <- runRWST m r s
+    return (a, w)
+{-# INLINE evalRWST #-}
+
+-- | Evaluate a computation with the given initial state and environment,
+-- returning the final state and output, discarding the final value.
+execRWST :: (Monad m)
+         => RWST r w s m a      -- ^computation to execute
+         -> r                   -- ^initial environment
+         -> s                   -- ^initial value
+         -> m (s, w)            -- ^computation yielding final state and output
+execRWST m r s = do
+    (_, s', w) <- runRWST m r s
+    return (s', w)
+{-# INLINE execRWST #-}
+
+-- | Map the inner computation using the given function.
+--
+-- * @'runRWST' ('mapRWST' f m) r s = f ('runRWST' m r s)@
+mapRWST :: (m (a, s, w) -> n (b, s, w')) -> RWST r w s m a -> RWST r w' s n b
+mapRWST f m = RWST $ \ r s -> f (runRWST m r s)
+{-# INLINE mapRWST #-}
+
+-- | @'withRWST' f m@ executes action @m@ with an initial environment
+-- and state modified by applying @f@.
+--
+-- * @'runRWST' ('withRWST' f m) r s = 'uncurry' ('runRWST' m) (f r s)@
+withRWST :: (r' -> s -> (r, s)) -> RWST r w s m a -> RWST r' w s m a
+withRWST f m = RWST $ \ r s -> uncurry (runRWST m) (f r s)
+{-# INLINE withRWST #-}
+
+instance (Functor m) => Functor (RWST r w s m) where
+    fmap f m = RWST $ \ r s ->
+        fmap (\ (a, s', w) -> (f a, s', w)) $ runRWST m r s
+    {-# INLINE fmap #-}
+
+instance (Monoid w, Functor m, Monad m) => Applicative (RWST r w s m) where
+    pure a = RWST $ \ _ s -> return (a, s, mempty)
+    {-# INLINE pure #-}
+    RWST mf <*> RWST mx = RWST $ \ r s -> do
+        (f, s', w)  <- mf r s
+        (x, s'',w') <- mx r s'
+        return (f x, s'', w `mappend` w')
+    {-# INLINE (<*>) #-}
+
+instance (Monoid w, Functor m, MonadPlus m) => Alternative (RWST r w s m) where
+    empty = RWST $ \ _ _ -> mzero
+    {-# INLINE empty #-}
+    RWST m <|> RWST n = RWST $ \ r s -> m r s `mplus` n r s
+    {-# INLINE (<|>) #-}
+
+instance (Monoid w, Monad m) => Monad (RWST r w s m) where
+#if !(MIN_VERSION_base(4,8,0))
+    return a = RWST $ \ _ s -> return (a, s, mempty)
+    {-# INLINE return #-}
+#endif
+    m >>= k  = RWST $ \ r s -> do
+        (a, s', w)  <- runRWST m r s
+        (b, s'',w') <- runRWST (k a) r s'
+        return (b, s'', w `mappend` w')
+    {-# INLINE (>>=) #-}
+#if !(MIN_VERSION_base(4,13,0))
+    fail msg = RWST $ \ _ _ -> fail msg
+    {-# INLINE fail #-}
+#endif
+
+#if MIN_VERSION_base(4,9,0)
+instance (Monoid w, Fail.MonadFail m) => Fail.MonadFail (RWST r w s m) where
+    fail msg = RWST $ \ _ _ -> Fail.fail msg
+    {-# INLINE fail #-}
+#endif
+
+instance (Monoid w, MonadPlus m) => MonadPlus (RWST r w s m) where
+    mzero = RWST $ \ _ _ -> mzero
+    {-# INLINE mzero #-}
+    RWST m `mplus` RWST n = RWST $ \ r s -> m r s `mplus` n r s
+    {-# INLINE mplus #-}
+
+instance (Monoid w, MonadFix m) => MonadFix (RWST r w s m) where
+    mfix f = RWST $ \ r s -> mfix $ \ ~(a, _, _) -> runRWST (f a) r s
+    {-# INLINE mfix #-}
+
+instance (Monoid w) => MonadTrans (RWST r w s) where
+    lift m = RWST $ \ _ s -> do
+        a <- m
+        return (a, s, mempty)
+    {-# INLINE lift #-}
+
+instance (Monoid w, MonadIO m) => MonadIO (RWST r w s m) where
+    liftIO = lift . liftIO
+    {-# INLINE liftIO #-}
+
+#if MIN_VERSION_base(4,12,0)
+instance Contravariant m => Contravariant (RWST r w s m) where
+    contramap f m = RWST $ \r s ->
+      contramap (\ (a, s', w) -> (f a, s', w)) $ runRWST m r s
+    {-# INLINE contramap #-}
+#endif
+
+-- ---------------------------------------------------------------------------
+-- Reader operations
+
+-- | Constructor for computations in the reader monad (equivalent to 'asks').
+reader :: (Monoid w, Monad m) => (r -> a) -> RWST r w s m a
+reader = asks
+{-# INLINE reader #-}
+
+-- | Fetch the value of the environment.
+ask :: (Monoid w, Monad m) => RWST r w s m r
+ask = RWST $ \ r s -> return (r, s, mempty)
+{-# INLINE ask #-}
+
+-- | Execute a computation in a modified environment
+--
+-- * @'runRWST' ('local' f m) r s = 'runRWST' m (f r) s@
+local :: (r -> r) -> RWST r w s m a -> RWST r w s m a
+local f m = RWST $ \ r s -> runRWST m (f r) s
+{-# INLINE local #-}
+
+-- | Retrieve a function of the current environment.
+--
+-- * @'asks' f = 'liftM' f 'ask'@
+asks :: (Monoid w, Monad m) => (r -> a) -> RWST r w s m a
+asks f = RWST $ \ r s -> return (f r, s, mempty)
+{-# INLINE asks #-}
+
+-- ---------------------------------------------------------------------------
+-- Writer operations
+
+-- | Construct a writer computation from a (result, output) pair.
+writer :: (Monad m) => (a, w) -> RWST r w s m a
+writer (a, w) = RWST $ \ _ s -> return (a, s, w)
+{-# INLINE writer #-}
+
+-- | @'tell' w@ is an action that produces the output @w@.
+tell :: (Monad m) => w -> RWST r w s m ()
+tell w = RWST $ \ _ s -> return ((),s,w)
+{-# INLINE tell #-}
+
+-- | @'listen' m@ is an action that executes the action @m@ and adds its
+-- output to the value of the computation.
+--
+-- * @'runRWST' ('listen' m) r s = 'liftM' (\\ (a, w) -> ((a, w), w)) ('runRWST' m r s)@
+listen :: (Monad m) => RWST r w s m a -> RWST r w s m (a, w)
+listen m = RWST $ \ r s -> do
+    (a, s', w) <- runRWST m r s
+    return ((a, w), s', w)
+{-# INLINE listen #-}
+
+-- | @'listens' f m@ is an action that executes the action @m@ and adds
+-- the result of applying @f@ to the output to the value of the computation.
+--
+-- * @'listens' f m = 'liftM' (id *** f) ('listen' m)@
+--
+-- * @'runRWST' ('listens' f m) r s = 'liftM' (\\ (a, w) -> ((a, f w), w)) ('runRWST' m r s)@
+listens :: (Monad m) => (w -> b) -> RWST r w s m a -> RWST r w s m (a, b)
+listens f m = RWST $ \ r s -> do
+    (a, s', w) <- runRWST m r s
+    return ((a, f w), s', w)
+{-# INLINE listens #-}
+
+-- | @'pass' m@ is an action that executes the action @m@, which returns
+-- a value and a function, and returns the value, applying the function
+-- to the output.
+--
+-- * @'runRWST' ('pass' m) r s = 'liftM' (\\ ((a, f), w) -> (a, f w)) ('runRWST' m r s)@
+pass :: (Monad m) => RWST r w s m (a, w -> w) -> RWST r w s m a
+pass m = RWST $ \ r s -> do
+    ((a, f), s', w) <- runRWST m r s
+    return (a, s', f w)
+{-# INLINE pass #-}
+
+-- | @'censor' f m@ is an action that executes the action @m@ and
+-- applies the function @f@ to its output, leaving the return value
+-- unchanged.
+--
+-- * @'censor' f m = 'pass' ('liftM' (\\ x -> (x,f)) m)@
+--
+-- * @'runRWST' ('censor' f m) r s = 'liftM' (\\ (a, w) -> (a, f w)) ('runRWST' m r s)@
+censor :: (Monad m) => (w -> w) -> RWST r w s m a -> RWST r w s m a
+censor f m = RWST $ \ r s -> do
+    (a, s', w) <- runRWST m r s
+    return (a, s', f w)
+{-# INLINE censor #-}
+
+-- ---------------------------------------------------------------------------
+-- State operations
+
+-- | Construct a state monad computation from a state transformer function.
+state :: (Monoid w, Monad m) => (s -> (a,s)) -> RWST r w s m a
+state f = RWST $ \ _ s -> case f s of (a,s') -> return (a, s', mempty)
+{-# INLINE state #-}
+
+-- | Fetch the current value of the state within the monad.
+get :: (Monoid w, Monad m) => RWST r w s m s
+get = RWST $ \ _ s -> return (s, s, mempty)
+{-# INLINE get #-}
+
+-- | @'put' s@ sets the state within the monad to @s@.
+put :: (Monoid w, Monad m) => s -> RWST r w s m ()
+put s = RWST $ \ _ _ -> return ((), s, mempty)
+{-# INLINE put #-}
+
+-- | @'modify' f@ is an action that updates the state to the result of
+-- applying @f@ to the current state.
+--
+-- * @'modify' f = 'get' >>= ('put' . f)@
+modify :: (Monoid w, Monad m) => (s -> s) -> RWST r w s m ()
+modify f = RWST $ \ _ s -> return ((), f s, mempty)
+{-# INLINE modify #-}
+
+-- | Get a specific component of the state, using a projection function
+-- supplied.
+--
+-- * @'gets' f = 'liftM' f 'get'@
+gets :: (Monoid w, Monad m) => (s -> a) -> RWST r w s m a
+gets f = RWST $ \ _ s -> return (f s, s, mempty)
+{-# INLINE gets #-}
+
+-- | Uniform lifting of a @callCC@ operation to the new monad.
+-- This version rolls back to the original state on entering the
+-- continuation.
+liftCallCC :: (Monoid w) =>
+    CallCC m (a,s,w) (b,s,w) -> CallCC (RWST r w s m) a b
+liftCallCC callCC f = RWST $ \ r s ->
+    callCC $ \ c ->
+    runRWST (f (\ a -> RWST $ \ _ _ -> c (a, s, mempty))) r s
+{-# INLINE liftCallCC #-}
+
+-- | In-situ lifting of a @callCC@ operation to the new monad.
+-- This version uses the current state on entering the continuation.
+liftCallCC' :: (Monoid w) =>
+    CallCC m (a,s,w) (b,s,w) -> CallCC (RWST r w s m) a b
+liftCallCC' callCC f = RWST $ \ r s ->
+    callCC $ \ c ->
+    runRWST (f (\ a -> RWST $ \ _ s' -> c (a, s', mempty))) r s
+{-# INLINE liftCallCC' #-}
+
+-- | Lift a @catchE@ operation to the new monad.
+liftCatch :: Catch e m (a,s,w) -> Catch e (RWST r w s m) a
+liftCatch catchE m h =
+    RWST $ \ r s -> runRWST m r s `catchE` \ e -> runRWST (h e) r s
+{-# INLINE liftCatch #-}

third_party/bazel/rules_haskell/examples/transformers/Control/Monad/Trans/Reader.hs

@@ -0,0 +1,262 @@
+{-# LANGUAGE CPP #-}
+#if __GLASGOW_HASKELL__ >= 702
+{-# LANGUAGE Safe #-}
+#endif
+#if __GLASGOW_HASKELL__ >= 710
+{-# LANGUAGE AutoDeriveTypeable #-}
+#endif
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Control.Monad.Trans.Reader
+-- Copyright   :  (c) Andy Gill 2001,
+--                (c) Oregon Graduate Institute of Science and Technology, 2001
+-- License     :  BSD-style (see the file LICENSE)
+--
+-- Maintainer  :  R.Paterson@city.ac.uk
+-- Stability   :  experimental
+-- Portability :  portable
+--
+-- Declaration of the 'ReaderT' monad transformer, which adds a static
+-- environment to a given monad.
+--
+-- If the computation is to modify the stored information, use
+-- "Control.Monad.Trans.State" instead.
+-----------------------------------------------------------------------------
+
+module Control.Monad.Trans.Reader (
+    -- * The Reader monad
+    Reader,
+    reader,
+    runReader,
+    mapReader,
+    withReader,
+    -- * The ReaderT monad transformer
+    ReaderT(..),
+    mapReaderT,
+    withReaderT,
+    -- * Reader operations
+    ask,
+    local,
+    asks,
+    -- * Lifting other operations
+    liftCallCC,
+    liftCatch,
+    ) where
+
+import Control.Monad.IO.Class
+import Control.Monad.Signatures
+import Control.Monad.Trans.Class
+#if MIN_VERSION_base(4,12,0)
+import Data.Functor.Contravariant
+#endif
+import Data.Functor.Identity
+
+import Control.Applicative
+import Control.Monad
+#if MIN_VERSION_base(4,9,0)
+import qualified Control.Monad.Fail as Fail
+#endif
+import Control.Monad.Fix
+#if !(MIN_VERSION_base(4,6,0))
+import Control.Monad.Instances ()  -- deprecated from base-4.6
+#endif
+#if MIN_VERSION_base(4,4,0)
+import Control.Monad.Zip (MonadZip(mzipWith))
+#endif
+#if MIN_VERSION_base(4,2,0)
+import Data.Functor(Functor(..))
+#endif
+
+-- | The parameterizable reader monad.
+--
+-- Computations are functions of a shared environment.
+--
+-- The 'return' function ignores the environment, while @>>=@ passes
+-- the inherited environment to both subcomputations.
+type Reader r = ReaderT r Identity
+
+-- | Constructor for computations in the reader monad (equivalent to 'asks').
+reader :: (Monad m) => (r -> a) -> ReaderT r m a
+reader f = ReaderT (return . f)
+{-# INLINE reader #-}
+
+-- | Runs a @Reader@ and extracts the final value from it.
+-- (The inverse of 'reader'.)
+runReader
+    :: Reader r a       -- ^ A @Reader@ to run.
+    -> r                -- ^ An initial environment.
+    -> a
+runReader m = runIdentity . runReaderT m
+{-# INLINE runReader #-}
+
+-- | Transform the value returned by a @Reader@.
+--
+-- * @'runReader' ('mapReader' f m) = f . 'runReader' m@
+mapReader :: (a -> b) -> Reader r a -> Reader r b
+mapReader f = mapReaderT (Identity . f . runIdentity)
+{-# INLINE mapReader #-}
+
+-- | Execute a computation in a modified environment
+-- (a specialization of 'withReaderT').
+--
+-- * @'runReader' ('withReader' f m) = 'runReader' m . f@
+withReader
+    :: (r' -> r)        -- ^ The function to modify the environment.
+    -> Reader r a       -- ^ Computation to run in the modified environment.
+    -> Reader r' a
+withReader = withReaderT
+{-# INLINE withReader #-}
+
+-- | The reader monad transformer,
+-- which adds a read-only environment to the given monad.
+--
+-- The 'return' function ignores the environment, while @>>=@ passes
+-- the inherited environment to both subcomputations.
+newtype ReaderT r m a = ReaderT { runReaderT :: r -> m a }
+
+-- | Transform the computation inside a @ReaderT@.
+--
+-- * @'runReaderT' ('mapReaderT' f m) = f . 'runReaderT' m@
+mapReaderT :: (m a -> n b) -> ReaderT r m a -> ReaderT r n b
+mapReaderT f m = ReaderT $ f . runReaderT m
+{-# INLINE mapReaderT #-}
+
+-- | Execute a computation in a modified environment
+-- (a more general version of 'local').
+--
+-- * @'runReaderT' ('withReaderT' f m) = 'runReaderT' m . f@
+withReaderT
+    :: (r' -> r)        -- ^ The function to modify the environment.
+    -> ReaderT r m a    -- ^ Computation to run in the modified environment.
+    -> ReaderT r' m a
+withReaderT f m = ReaderT $ runReaderT m . f
+{-# INLINE withReaderT #-}
+
+instance (Functor m) => Functor (ReaderT r m) where
+    fmap f  = mapReaderT (fmap f)
+    {-# INLINE fmap #-}
+#if MIN_VERSION_base(4,2,0)
+    x <$ v = mapReaderT (x <$) v
+    {-# INLINE (<$) #-}
+#endif
+
+instance (Applicative m) => Applicative (ReaderT r m) where
+    pure    = liftReaderT . pure
+    {-# INLINE pure #-}
+    f <*> v = ReaderT $ \ r -> runReaderT f r <*> runReaderT v r
+    {-# INLINE (<*>) #-}
+#if MIN_VERSION_base(4,2,0)
+    u *> v = ReaderT $ \ r -> runReaderT u r *> runReaderT v r
+    {-# INLINE (*>) #-}
+    u <* v = ReaderT $ \ r -> runReaderT u r <* runReaderT v r
+    {-# INLINE (<*) #-}
+#endif
+#if MIN_VERSION_base(4,10,0)
+    liftA2 f x y = ReaderT $ \ r -> liftA2 f (runReaderT x r) (runReaderT y r)
+    {-# INLINE liftA2 #-}
+#endif
+
+instance (Alternative m) => Alternative (ReaderT r m) where
+    empty   = liftReaderT empty
+    {-# INLINE empty #-}
+    m <|> n = ReaderT $ \ r -> runReaderT m r <|> runReaderT n r
+    {-# INLINE (<|>) #-}
+
+instance (Monad m) => Monad (ReaderT r m) where
+#if !(MIN_VERSION_base(4,8,0))
+    return   = lift . return
+    {-# INLINE return #-}
+#endif
+    m >>= k  = ReaderT $ \ r -> do
+        a <- runReaderT m r
+        runReaderT (k a) r
+    {-# INLINE (>>=) #-}
+#if MIN_VERSION_base(4,8,0)
+    (>>) = (*>)
+#else
+    m >> k = ReaderT $ \ r -> runReaderT m r >> runReaderT k r
+#endif
+    {-# INLINE (>>) #-}
+#if !(MIN_VERSION_base(4,13,0))
+    fail msg = lift (fail msg)
+    {-# INLINE fail #-}
+#endif
+
+#if MIN_VERSION_base(4,9,0)
+instance (Fail.MonadFail m) => Fail.MonadFail (ReaderT r m) where
+    fail msg = lift (Fail.fail msg)
+    {-# INLINE fail #-}
+#endif
+
+instance (MonadPlus m) => MonadPlus (ReaderT r m) where
+    mzero       = lift mzero
+    {-# INLINE mzero #-}
+    m `mplus` n = ReaderT $ \ r -> runReaderT m r `mplus` runReaderT n r
+    {-# INLINE mplus #-}
+
+instance (MonadFix m) => MonadFix (ReaderT r m) where
+    mfix f = ReaderT $ \ r -> mfix $ \ a -> runReaderT (f a) r
+    {-# INLINE mfix #-}
+
+instance MonadTrans (ReaderT r) where
+    lift   = liftReaderT
+    {-# INLINE lift #-}
+
+instance (MonadIO m) => MonadIO (ReaderT r m) where
+    liftIO = lift . liftIO
+    {-# INLINE liftIO #-}
+
+#if MIN_VERSION_base(4,4,0)
+instance (MonadZip m) => MonadZip (ReaderT r m) where
+    mzipWith f (ReaderT m) (ReaderT n) = ReaderT $ \ a ->
+        mzipWith f (m a) (n a)
+    {-# INLINE mzipWith #-}
+#endif
+
+#if MIN_VERSION_base(4,12,0)
+instance Contravariant m => Contravariant (ReaderT r m) where
+    contramap f = ReaderT . fmap (contramap f) . runReaderT
+    {-# INLINE contramap #-}
+#endif
+
+liftReaderT :: m a -> ReaderT r m a
+liftReaderT m = ReaderT (const m)
+{-# INLINE liftReaderT #-}
+
+-- | Fetch the value of the environment.
+ask :: (Monad m) => ReaderT r m r
+ask = ReaderT return
+{-# INLINE ask #-}
+
+-- | Execute a computation in a modified environment
+-- (a specialization of 'withReaderT').
+--
+-- * @'runReaderT' ('local' f m) = 'runReaderT' m . f@
+local
+    :: (r -> r)         -- ^ The function to modify the environment.
+    -> ReaderT r m a    -- ^ Computation to run in the modified environment.
+    -> ReaderT r m a
+local = withReaderT
+{-# INLINE local #-}
+
+-- | Retrieve a function of the current environment.
+--
+-- * @'asks' f = 'liftM' f 'ask'@
+asks :: (Monad m)
+    => (r -> a)         -- ^ The selector function to apply to the environment.
+    -> ReaderT r m a
+asks f = ReaderT (return . f)
+{-# INLINE asks #-}
+
+-- | Lift a @callCC@ operation to the new monad.
+liftCallCC :: CallCC m a b -> CallCC (ReaderT r m) a b
+liftCallCC callCC f = ReaderT $ \ r ->
+    callCC $ \ c ->
+    runReaderT (f (ReaderT . const . c)) r
+{-# INLINE liftCallCC #-}
+
+-- | Lift a @catchE@ operation to the new monad.
+liftCatch :: Catch e m a -> Catch e (ReaderT r m) a
+liftCatch f m h =
+    ReaderT $ \ r -> f (runReaderT m r) (\ e -> runReaderT (h e) r)
+{-# INLINE liftCatch #-}

third_party/bazel/rules_haskell/examples/transformers/Control/Monad/Trans/Select.hs

@@ -0,0 +1,161 @@
+{-# LANGUAGE CPP #-}
+#if __GLASGOW_HASKELL__ >= 702
+{-# LANGUAGE Safe #-}
+#endif
+#if __GLASGOW_HASKELL__ >= 706
+{-# LANGUAGE PolyKinds #-}
+#endif
+#if __GLASGOW_HASKELL__ >= 710
+{-# LANGUAGE AutoDeriveTypeable #-}
+#endif
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Control.Monad.Trans.Select
+-- Copyright   :  (c) Ross Paterson 2017
+-- License     :  BSD-style (see the file LICENSE)
+--
+-- Maintainer  :  R.Paterson@city.ac.uk
+-- Stability   :  experimental
+-- Portability :  portable
+--
+-- Selection monad transformer, modelling search algorithms.
+--
+-- * Martin Escardo and Paulo Oliva.
+--   "Selection functions, bar recursion and backward induction",
+--   /Mathematical Structures in Computer Science/ 20:2 (2010), pp. 127-168.
+--   <https://www.cs.bham.ac.uk/~mhe/papers/selection-escardo-oliva.pdf>
+--
+-- * Jules Hedges. "Monad transformers for backtracking search".
+--   In /Proceedings of MSFP 2014/. <https://arxiv.org/abs/1406.2058>
+-----------------------------------------------------------------------------
+
+module Control.Monad.Trans.Select (
+    -- * The Select monad
+    Select,
+    select,
+    runSelect,
+    mapSelect,
+    -- * The SelectT monad transformer
+    SelectT(SelectT),
+    runSelectT,
+    mapSelectT,
+    -- * Monad transformation
+    selectToContT,
+    selectToCont,
+    ) where
+
+import Control.Monad.IO.Class
+import Control.Monad.Trans.Class
+import Control.Monad.Trans.Cont
+
+import Control.Applicative
+import Control.Monad
+#if MIN_VERSION_base(4,9,0)
+import qualified Control.Monad.Fail as Fail
+#endif
+import Data.Functor.Identity
+
+-- | Selection monad.
+type Select r = SelectT r Identity
+
+-- | Constructor for computations in the selection monad.
+select :: ((a -> r) -> a) -> Select r a
+select f = SelectT $ \ k -> Identity (f (runIdentity . k))
+{-# INLINE select #-}
+
+-- | Runs a @Select@ computation with a function for evaluating answers
+-- to select a particular answer.  (The inverse of 'select'.)
+runSelect :: Select r a -> (a -> r) -> a
+runSelect m k = runIdentity (runSelectT m (Identity . k))
+{-# INLINE runSelect #-}
+
+-- | Apply a function to transform the result of a selection computation.
+--
+-- * @'runSelect' ('mapSelect' f m) = f . 'runSelect' m@
+mapSelect :: (a -> a) -> Select r a -> Select r a
+mapSelect f = mapSelectT (Identity . f . runIdentity)
+{-# INLINE mapSelect #-}
+
+-- | Selection monad transformer.
+--
+-- 'SelectT' is not a functor on the category of monads, and many operations
+-- cannot be lifted through it.
+newtype SelectT r m a = SelectT ((a -> m r) -> m a)
+
+-- | Runs a @SelectT@ computation with a function for evaluating answers
+-- to select a particular answer.  (The inverse of 'select'.)
+runSelectT :: SelectT r m a -> (a -> m r) -> m a
+runSelectT (SelectT g) = g
+{-# INLINE runSelectT #-}
+
+-- | Apply a function to transform the result of a selection computation.
+-- This has a more restricted type than the @map@ operations for other
+-- monad transformers, because 'SelectT' does not define a functor in
+-- the category of monads.
+--
+-- * @'runSelectT' ('mapSelectT' f m) = f . 'runSelectT' m@
+mapSelectT :: (m a -> m a) -> SelectT r m a -> SelectT r m a
+mapSelectT f m = SelectT $ f . runSelectT m
+{-# INLINE mapSelectT #-}
+
+instance (Functor m) => Functor (SelectT r m) where
+    fmap f (SelectT g) = SelectT (fmap f . g . (. f))
+    {-# INLINE fmap #-}
+
+instance (Functor m, Monad m) => Applicative (SelectT r m) where
+    pure = lift . return
+    {-# INLINE pure #-}
+    SelectT gf <*> SelectT gx = SelectT $ \ k -> do
+        let h f = liftM f (gx (k . f))
+        f <- gf ((>>= k) . h)
+        h f
+    {-# INLINE (<*>) #-}
+    m *> k = m >>= \_ -> k
+    {-# INLINE (*>) #-}
+
+instance (Functor m, MonadPlus m) => Alternative (SelectT r m) where
+    empty = mzero
+    {-# INLINE empty #-}
+    (<|>) = mplus
+    {-# INLINE (<|>) #-}
+
+instance (Monad m) => Monad (SelectT r m) where
+#if !(MIN_VERSION_base(4,8,0))
+    return = lift . return
+    {-# INLINE return #-}
+#endif
+    SelectT g >>= f = SelectT $ \ k -> do
+        let h x = runSelectT (f x) k
+        y <- g ((>>= k) . h)
+        h y
+    {-# INLINE (>>=) #-}
+
+#if MIN_VERSION_base(4,9,0)
+instance (Fail.MonadFail m) => Fail.MonadFail (SelectT r m) where
+    fail msg = lift (Fail.fail msg)
+    {-# INLINE fail #-}
+#endif
+
+instance (MonadPlus m) => MonadPlus (SelectT r m) where
+    mzero = SelectT (const mzero)
+    {-# INLINE mzero #-}
+    SelectT f `mplus` SelectT g = SelectT $ \ k -> f k `mplus` g k
+    {-# INLINE mplus #-}
+
+instance MonadTrans (SelectT r) where
+    lift = SelectT . const
+    {-# INLINE lift #-}
+
+instance (MonadIO m) => MonadIO (SelectT r m) where
+    liftIO = lift . liftIO
+    {-# INLINE liftIO #-}
+
+-- | Convert a selection computation to a continuation-passing computation.
+selectToContT :: (Monad m) => SelectT r m a -> ContT r m a
+selectToContT (SelectT g) = ContT $ \ k -> g k >>= k
+{-# INLINE selectToCont #-}
+
+-- | Deprecated name for 'selectToContT'.
+{-# DEPRECATED selectToCont "Use selectToContT instead" #-}
+selectToCont :: (Monad m) => SelectT r m a -> ContT r m a
+selectToCont = selectToContT

third_party/bazel/rules_haskell/examples/transformers/Control/Monad/Trans/State.hs

@@ -0,0 +1,33 @@
+{-# LANGUAGE CPP #-}
+#if __GLASGOW_HASKELL__ >= 702
+{-# LANGUAGE Safe #-}
+#endif
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Control.Monad.Trans.State
+-- Copyright   :  (c) Andy Gill 2001,
+--                (c) Oregon Graduate Institute of Science and Technology, 2001
+-- License     :  BSD-style (see the file LICENSE)
+--
+-- Maintainer  :  R.Paterson@city.ac.uk
+-- Stability   :  experimental
+-- Portability :  portable
+--
+-- State monads, passing an updatable state through a computation.
+--
+-- Some computations may not require the full power of state transformers:
+--
+-- * For a read-only state, see "Control.Monad.Trans.Reader".
+--
+-- * To accumulate a value without using it on the way, see
+--   "Control.Monad.Trans.Writer".
+--
+-- This version is lazy; for a strict version, see
+-- "Control.Monad.Trans.State.Strict", which has the same interface.
+-----------------------------------------------------------------------------
+
+module Control.Monad.Trans.State (
+  module Control.Monad.Trans.State.Lazy
+  ) where
+
+import Control.Monad.Trans.State.Lazy

third_party/bazel/rules_haskell/examples/transformers/Control/Monad/Trans/State/Lazy.hs

@@ -0,0 +1,428 @@
+{-# LANGUAGE CPP #-}
+#if __GLASGOW_HASKELL__ >= 702
+{-# LANGUAGE Safe #-}
+#endif
+#if __GLASGOW_HASKELL__ >= 710
+{-# LANGUAGE AutoDeriveTypeable #-}
+#endif
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Control.Monad.Trans.State.Lazy
+-- Copyright   :  (c) Andy Gill 2001,
+--                (c) Oregon Graduate Institute of Science and Technology, 2001
+-- License     :  BSD-style (see the file LICENSE)
+--
+-- Maintainer  :  R.Paterson@city.ac.uk
+-- Stability   :  experimental
+-- Portability :  portable
+--
+-- Lazy state monads, passing an updatable state through a computation.
+-- See below for examples.
+--
+-- Some computations may not require the full power of state transformers:
+--
+-- * For a read-only state, see "Control.Monad.Trans.Reader".
+--
+-- * To accumulate a value without using it on the way, see
+--   "Control.Monad.Trans.Writer".
+--
+-- In this version, sequencing of computations is lazy, so that for
+-- example the following produces a usable result:
+--
+-- > evalState (sequence $ repeat $ do { n <- get; put (n*2); return n }) 1
+--
+-- For a strict version with the same interface, see
+-- "Control.Monad.Trans.State.Strict".
+-----------------------------------------------------------------------------
+
+module Control.Monad.Trans.State.Lazy (
+    -- * The State monad
+    State,
+    state,
+    runState,
+    evalState,
+    execState,
+    mapState,
+    withState,
+    -- * The StateT monad transformer
+    StateT(..),
+    evalStateT,
+    execStateT,
+    mapStateT,
+    withStateT,
+    -- * State operations
+    get,
+    put,
+    modify,
+    modify',
+    gets,
+    -- * Lifting other operations
+    liftCallCC,
+    liftCallCC',
+    liftCatch,
+    liftListen,
+    liftPass,
+    -- * Examples
+    -- ** State monads
+    -- $examples
+
+    -- ** Counting
+    -- $counting
+
+    -- ** Labelling trees
+    -- $labelling
+  ) where
+
+import Control.Monad.IO.Class
+import Control.Monad.Signatures
+import Control.Monad.Trans.Class
+#if MIN_VERSION_base(4,12,0)
+import Data.Functor.Contravariant
+#endif
+import Data.Functor.Identity
+
+import Control.Applicative
+import Control.Monad
+#if MIN_VERSION_base(4,9,0)
+import qualified Control.Monad.Fail as Fail
+#endif
+import Control.Monad.Fix
+
+-- ---------------------------------------------------------------------------
+-- | A state monad parameterized by the type @s@ of the state to carry.
+--
+-- The 'return' function leaves the state unchanged, while @>>=@ uses
+-- the final state of the first computation as the initial state of
+-- the second.
+type State s = StateT s Identity
+
+-- | Construct a state monad computation from a function.
+-- (The inverse of 'runState'.)
+state :: (Monad m)
+      => (s -> (a, s))  -- ^pure state transformer
+      -> StateT s m a   -- ^equivalent state-passing computation
+state f = StateT (return . f)
+{-# INLINE state #-}
+
+-- | Unwrap a state monad computation as a function.
+-- (The inverse of 'state'.)
+runState :: State s a   -- ^state-passing computation to execute
+         -> s           -- ^initial state
+         -> (a, s)      -- ^return value and final state
+runState m = runIdentity . runStateT m
+{-# INLINE runState #-}
+
+-- | Evaluate a state computation with the given initial state
+-- and return the final value, discarding the final state.
+--
+-- * @'evalState' m s = 'fst' ('runState' m s)@
+evalState :: State s a  -- ^state-passing computation to execute
+          -> s          -- ^initial value
+          -> a          -- ^return value of the state computation
+evalState m s = fst (runState m s)
+{-# INLINE evalState #-}
+
+-- | Evaluate a state computation with the given initial state
+-- and return the final state, discarding the final value.
+--
+-- * @'execState' m s = 'snd' ('runState' m s)@
+execState :: State s a  -- ^state-passing computation to execute
+          -> s          -- ^initial value
+          -> s          -- ^final state
+execState m s = snd (runState m s)
+{-# INLINE execState #-}
+
+-- | Map both the return value and final state of a computation using
+-- the given function.
+--
+-- * @'runState' ('mapState' f m) = f . 'runState' m@
+mapState :: ((a, s) -> (b, s)) -> State s a -> State s b
+mapState f = mapStateT (Identity . f . runIdentity)
+{-# INLINE mapState #-}
+
+-- | @'withState' f m@ executes action @m@ on a state modified by
+-- applying @f@.
+--
+-- * @'withState' f m = 'modify' f >> m@
+withState :: (s -> s) -> State s a -> State s a
+withState = withStateT
+{-# INLINE withState #-}
+
+-- ---------------------------------------------------------------------------
+-- | A state transformer monad parameterized by:
+--
+--   * @s@ - The state.
+--
+--   * @m@ - The inner monad.
+--
+-- The 'return' function leaves the state unchanged, while @>>=@ uses
+-- the final state of the first computation as the initial state of
+-- the second.
+newtype StateT s m a = StateT { runStateT :: s -> m (a,s) }
+
+-- | Evaluate a state computation with the given initial state
+-- and return the final value, discarding the final state.
+--
+-- * @'evalStateT' m s = 'liftM' 'fst' ('runStateT' m s)@
+evalStateT :: (Monad m) => StateT s m a -> s -> m a
+evalStateT m s = do
+    ~(a, _) <- runStateT m s
+    return a
+{-# INLINE evalStateT #-}
+
+-- | Evaluate a state computation with the given initial state
+-- and return the final state, discarding the final value.
+--
+-- * @'execStateT' m s = 'liftM' 'snd' ('runStateT' m s)@
+execStateT :: (Monad m) => StateT s m a -> s -> m s
+execStateT m s = do
+    ~(_, s') <- runStateT m s
+    return s'
+{-# INLINE execStateT #-}
+
+-- | Map both the return value and final state of a computation using
+-- the given function.
+--
+-- * @'runStateT' ('mapStateT' f m) = f . 'runStateT' m@
+mapStateT :: (m (a, s) -> n (b, s)) -> StateT s m a -> StateT s n b
+mapStateT f m = StateT $ f . runStateT m
+{-# INLINE mapStateT #-}
+
+-- | @'withStateT' f m@ executes action @m@ on a state modified by
+-- applying @f@.
+--
+-- * @'withStateT' f m = 'modify' f >> m@
+withStateT :: (s -> s) -> StateT s m a -> StateT s m a
+withStateT f m = StateT $ runStateT m . f
+{-# INLINE withStateT #-}
+
+instance (Functor m) => Functor (StateT s m) where
+    fmap f m = StateT $ \ s ->
+        fmap (\ ~(a, s') -> (f a, s')) $ runStateT m s
+    {-# INLINE fmap #-}
+
+instance (Functor m, Monad m) => Applicative (StateT s m) where
+    pure a = StateT $ \ s -> return (a, s)
+    {-# INLINE pure #-}
+    StateT mf <*> StateT mx = StateT $ \ s -> do
+        ~(f, s') <- mf s
+        ~(x, s'') <- mx s'
+        return (f x, s'')
+    {-# INLINE (<*>) #-}
+    m *> k = m >>= \_ -> k
+    {-# INLINE (*>) #-}
+
+instance (Functor m, MonadPlus m) => Alternative (StateT s m) where
+    empty = StateT $ \ _ -> mzero
+    {-# INLINE empty #-}
+    StateT m <|> StateT n = StateT $ \ s -> m s `mplus` n s
+    {-# INLINE (<|>) #-}
+
+instance (Monad m) => Monad (StateT s m) where
+#if !(MIN_VERSION_base(4,8,0))
+    return a = StateT $ \ s -> return (a, s)
+    {-# INLINE return #-}
+#endif
+    m >>= k  = StateT $ \ s -> do
+        ~(a, s') <- runStateT m s
+        runStateT (k a) s'
+    {-# INLINE (>>=) #-}
+#if !(MIN_VERSION_base(4,13,0))
+    fail str = StateT $ \ _ -> fail str
+    {-# INLINE fail #-}
+#endif
+
+#if MIN_VERSION_base(4,9,0)
+instance (Fail.MonadFail m) => Fail.MonadFail (StateT s m) where
+    fail str = StateT $ \ _ -> Fail.fail str
+    {-# INLINE fail #-}
+#endif
+
+instance (MonadPlus m) => MonadPlus (StateT s m) where
+    mzero       = StateT $ \ _ -> mzero
+    {-# INLINE mzero #-}
+    StateT m `mplus` StateT n = StateT $ \ s -> m s `mplus` n s
+    {-# INLINE mplus #-}
+
+instance (MonadFix m) => MonadFix (StateT s m) where
+    mfix f = StateT $ \ s -> mfix $ \ ~(a, _) -> runStateT (f a) s
+    {-# INLINE mfix #-}
+
+instance MonadTrans (StateT s) where
+    lift m = StateT $ \ s -> do
+        a <- m
+        return (a, s)
+    {-# INLINE lift #-}
+
+instance (MonadIO m) => MonadIO (StateT s m) where
+    liftIO = lift . liftIO
+    {-# INLINE liftIO #-}
+
+#if MIN_VERSION_base(4,12,0)
+instance Contravariant m => Contravariant (StateT s m) where
+    contramap f m = StateT $ \s ->
+      contramap (\ ~(a, s') -> (f a, s')) $ runStateT m s
+    {-# INLINE contramap #-}
+#endif
+
+-- | Fetch the current value of the state within the monad.
+get :: (Monad m) => StateT s m s
+get = state $ \ s -> (s, s)
+{-# INLINE get #-}
+
+-- | @'put' s@ sets the state within the monad to @s@.
+put :: (Monad m) => s -> StateT s m ()
+put s = state $ \ _ -> ((), s)
+{-# INLINE put #-}
+
+-- | @'modify' f@ is an action that updates the state to the result of
+-- applying @f@ to the current state.
+--
+-- * @'modify' f = 'get' >>= ('put' . f)@
+modify :: (Monad m) => (s -> s) -> StateT s m ()
+modify f = state $ \ s -> ((), f s)
+{-# INLINE modify #-}
+
+-- | A variant of 'modify' in which the computation is strict in the
+-- new state.
+--
+-- * @'modify'' f = 'get' >>= (('$!') 'put' . f)@
+modify' :: (Monad m) => (s -> s) -> StateT s m ()
+modify' f = do
+    s <- get
+    put $! f s
+{-# INLINE modify' #-}
+
+-- | Get a specific component of the state, using a projection function
+-- supplied.
+--
+-- * @'gets' f = 'liftM' f 'get'@
+gets :: (Monad m) => (s -> a) -> StateT s m a
+gets f = state $ \ s -> (f s, s)
+{-# INLINE gets #-}
+
+-- | Uniform lifting of a @callCC@ operation to the new monad.
+-- This version rolls back to the original state on entering the
+-- continuation.
+liftCallCC :: CallCC m (a,s) (b,s) -> CallCC (StateT s m) a b
+liftCallCC callCC f = StateT $ \ s ->
+    callCC $ \ c ->
+    runStateT (f (\ a -> StateT $ \ _ -> c (a, s))) s
+{-# INLINE liftCallCC #-}
+
+-- | In-situ lifting of a @callCC@ operation to the new monad.
+-- This version uses the current state on entering the continuation.
+-- It does not satisfy the uniformity property (see "Control.Monad.Signatures").
+liftCallCC' :: CallCC m (a,s) (b,s) -> CallCC (StateT s m) a b
+liftCallCC' callCC f = StateT $ \ s ->
+    callCC $ \ c ->
+    runStateT (f (\ a -> StateT $ \ s' -> c (a, s'))) s
+{-# INLINE liftCallCC' #-}
+
+-- | Lift a @catchE@ operation to the new monad.
+liftCatch :: Catch e m (a,s) -> Catch e (StateT s m) a
+liftCatch catchE m h =
+    StateT $ \ s -> runStateT m s `catchE` \ e -> runStateT (h e) s
+{-# INLINE liftCatch #-}
+
+-- | Lift a @listen@ operation to the new monad.
+liftListen :: (Monad m) => Listen w m (a,s) -> Listen w (StateT s m) a
+liftListen listen m = StateT $ \ s -> do
+    ~((a, s'), w) <- listen (runStateT m s)
+    return ((a, w), s')
+{-# INLINE liftListen #-}
+
+-- | Lift a @pass@ operation to the new monad.
+liftPass :: (Monad m) => Pass w m (a,s) -> Pass w (StateT s m) a
+liftPass pass m = StateT $ \ s -> pass $ do
+    ~((a, f), s') <- runStateT m s
+    return ((a, s'), f)
+{-# INLINE liftPass #-}
+
+{- $examples
+
+Parser from ParseLib with Hugs:
+
+> type Parser a = StateT String [] a
+>    ==> StateT (String -> [(a,String)])
+
+For example, item can be written as:
+
+> item = do (x:xs) <- get
+>        put xs
+>        return x
+>
+> type BoringState s a = StateT s Identity a
+>      ==> StateT (s -> Identity (a,s))
+>
+> type StateWithIO s a = StateT s IO a
+>      ==> StateT (s -> IO (a,s))
+>
+> type StateWithErr s a = StateT s Maybe a
+>      ==> StateT (s -> Maybe (a,s))
+
+-}
+
+{- $counting
+
+A function to increment a counter.
+Taken from the paper \"Generalising Monads to Arrows\",
+John Hughes (<http://www.cse.chalmers.se/~rjmh/>), November 1998:
+
+> tick :: State Int Int
+> tick = do n <- get
+>           put (n+1)
+>           return n
+
+Add one to the given number using the state monad:
+
+> plusOne :: Int -> Int
+> plusOne n = execState tick n
+
+A contrived addition example. Works only with positive numbers:
+
+> plus :: Int -> Int -> Int
+> plus n x = execState (sequence $ replicate n tick) x
+
+-}
+
+{- $labelling
+
+An example from /The Craft of Functional Programming/, Simon
+Thompson (<http://www.cs.kent.ac.uk/people/staff/sjt/>),
+Addison-Wesley 1999: \"Given an arbitrary tree, transform it to a
+tree of integers in which the original elements are replaced by
+natural numbers, starting from 0.  The same element has to be
+replaced by the same number at every occurrence, and when we meet
+an as-yet-unvisited element we have to find a \'new\' number to match
+it with:\"
+
+> data Tree a = Nil | Node a (Tree a) (Tree a) deriving (Show, Eq)
+> type Table a = [a]
+
+> numberTree :: Eq a => Tree a -> State (Table a) (Tree Int)
+> numberTree Nil = return Nil
+> numberTree (Node x t1 t2) = do
+>     num <- numberNode x
+>     nt1 <- numberTree t1
+>     nt2 <- numberTree t2
+>     return (Node num nt1 nt2)
+>   where
+>     numberNode :: Eq a => a -> State (Table a) Int
+>     numberNode x = do
+>         table <- get
+>         case elemIndex x table of
+>             Nothing -> do
+>                 put (table ++ [x])
+>                 return (length table)
+>             Just i -> return i
+
+numTree applies numberTree with an initial state:
+
+> numTree :: (Eq a) => Tree a -> Tree Int
+> numTree t = evalState (numberTree t) []
+
+> testTree = Node "Zero" (Node "One" (Node "Two" Nil Nil) (Node "One" (Node "Zero" Nil Nil) Nil)) Nil
+> numTree testTree => Node 0 (Node 1 (Node 2 Nil Nil) (Node 1 (Node 0 Nil Nil) Nil)) Nil
+
+-}

third_party/bazel/rules_haskell/examples/transformers/Control/Monad/Trans/State/Strict.hs

@@ -0,0 +1,425 @@
+{-# LANGUAGE CPP #-}
+#if __GLASGOW_HASKELL__ >= 702
+{-# LANGUAGE Safe #-}
+#endif
+#if __GLASGOW_HASKELL__ >= 710
+{-# LANGUAGE AutoDeriveTypeable #-}
+#endif
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Control.Monad.Trans.State.Strict
+-- Copyright   :  (c) Andy Gill 2001,
+--                (c) Oregon Graduate Institute of Science and Technology, 2001
+-- License     :  BSD-style (see the file LICENSE)
+--
+-- Maintainer  :  R.Paterson@city.ac.uk
+-- Stability   :  experimental
+-- Portability :  portable
+--
+-- Strict state monads, passing an updatable state through a computation.
+-- See below for examples.
+--
+-- Some computations may not require the full power of state transformers:
+--
+-- * For a read-only state, see "Control.Monad.Trans.Reader".
+--
+-- * To accumulate a value without using it on the way, see
+--   "Control.Monad.Trans.Writer".
+--
+-- In this version, sequencing of computations is strict (but computations
+-- are not strict in the state unless you force it with 'seq' or the like).
+-- For a lazy version with the same interface, see
+-- "Control.Monad.Trans.State.Lazy".
+-----------------------------------------------------------------------------
+
+module Control.Monad.Trans.State.Strict (
+    -- * The State monad
+    State,
+    state,
+    runState,
+    evalState,
+    execState,
+    mapState,
+    withState,
+    -- * The StateT monad transformer
+    StateT(..),
+    evalStateT,
+    execStateT,
+    mapStateT,
+    withStateT,
+    -- * State operations
+    get,
+    put,
+    modify,
+    modify',
+    gets,
+    -- * Lifting other operations
+    liftCallCC,
+    liftCallCC',
+    liftCatch,
+    liftListen,
+    liftPass,
+    -- * Examples
+    -- ** State monads
+    -- $examples
+
+    -- ** Counting
+    -- $counting
+
+    -- ** Labelling trees
+    -- $labelling
+  ) where
+
+import Control.Monad.IO.Class
+import Control.Monad.Signatures
+import Control.Monad.Trans.Class
+#if MIN_VERSION_base(4,12,0)
+import Data.Functor.Contravariant
+#endif
+import Data.Functor.Identity
+
+import Control.Applicative
+import Control.Monad
+#if MIN_VERSION_base(4,9,0)
+import qualified Control.Monad.Fail as Fail
+#endif
+import Control.Monad.Fix
+
+-- ---------------------------------------------------------------------------
+-- | A state monad parameterized by the type @s@ of the state to carry.
+--
+-- The 'return' function leaves the state unchanged, while @>>=@ uses
+-- the final state of the first computation as the initial state of
+-- the second.
+type State s = StateT s Identity
+
+-- | Construct a state monad computation from a function.
+-- (The inverse of 'runState'.)
+state :: (Monad m)
+      => (s -> (a, s))  -- ^pure state transformer
+      -> StateT s m a   -- ^equivalent state-passing computation
+state f = StateT (return . f)
+{-# INLINE state #-}
+
+-- | Unwrap a state monad computation as a function.
+-- (The inverse of 'state'.)
+runState :: State s a   -- ^state-passing computation to execute
+         -> s           -- ^initial state
+         -> (a, s)      -- ^return value and final state
+runState m = runIdentity . runStateT m
+{-# INLINE runState #-}
+
+-- | Evaluate a state computation with the given initial state
+-- and return the final value, discarding the final state.
+--
+-- * @'evalState' m s = 'fst' ('runState' m s)@
+evalState :: State s a  -- ^state-passing computation to execute
+          -> s          -- ^initial value
+          -> a          -- ^return value of the state computation
+evalState m s = fst (runState m s)
+{-# INLINE evalState #-}
+
+-- | Evaluate a state computation with the given initial state
+-- and return the final state, discarding the final value.
+--
+-- * @'execState' m s = 'snd' ('runState' m s)@
+execState :: State s a  -- ^state-passing computation to execute
+          -> s          -- ^initial value
+          -> s          -- ^final state
+execState m s = snd (runState m s)
+{-# INLINE execState #-}
+
+-- | Map both the return value and final state of a computation using
+-- the given function.
+--
+-- * @'runState' ('mapState' f m) = f . 'runState' m@
+mapState :: ((a, s) -> (b, s)) -> State s a -> State s b
+mapState f = mapStateT (Identity . f . runIdentity)
+{-# INLINE mapState #-}
+
+-- | @'withState' f m@ executes action @m@ on a state modified by
+-- applying @f@.
+--
+-- * @'withState' f m = 'modify' f >> m@
+withState :: (s -> s) -> State s a -> State s a
+withState = withStateT
+{-# INLINE withState #-}
+
+-- ---------------------------------------------------------------------------
+-- | A state transformer monad parameterized by:
+--
+--   * @s@ - The state.
+--
+--   * @m@ - The inner monad.
+--
+-- The 'return' function leaves the state unchanged, while @>>=@ uses
+-- the final state of the first computation as the initial state of
+-- the second.
+newtype StateT s m a = StateT { runStateT :: s -> m (a,s) }
+
+-- | Evaluate a state computation with the given initial state
+-- and return the final value, discarding the final state.
+--
+-- * @'evalStateT' m s = 'liftM' 'fst' ('runStateT' m s)@
+evalStateT :: (Monad m) => StateT s m a -> s -> m a
+evalStateT m s = do
+    (a, _) <- runStateT m s
+    return a
+{-# INLINE evalStateT #-}
+
+-- | Evaluate a state computation with the given initial state
+-- and return the final state, discarding the final value.
+--
+-- * @'execStateT' m s = 'liftM' 'snd' ('runStateT' m s)@
+execStateT :: (Monad m) => StateT s m a -> s -> m s
+execStateT m s = do
+    (_, s') <- runStateT m s
+    return s'
+{-# INLINE execStateT #-}
+
+-- | Map both the return value and final state of a computation using
+-- the given function.
+--
+-- * @'runStateT' ('mapStateT' f m) = f . 'runStateT' m@
+mapStateT :: (m (a, s) -> n (b, s)) -> StateT s m a -> StateT s n b
+mapStateT f m = StateT $ f . runStateT m
+{-# INLINE mapStateT #-}
+
+-- | @'withStateT' f m@ executes action @m@ on a state modified by
+-- applying @f@.
+--
+-- * @'withStateT' f m = 'modify' f >> m@
+withStateT :: (s -> s) -> StateT s m a -> StateT s m a
+withStateT f m = StateT $ runStateT m . f
+{-# INLINE withStateT #-}
+
+instance (Functor m) => Functor (StateT s m) where
+    fmap f m = StateT $ \ s ->
+        fmap (\ (a, s') -> (f a, s')) $ runStateT m s
+    {-# INLINE fmap #-}
+
+instance (Functor m, Monad m) => Applicative (StateT s m) where
+    pure a = StateT $ \ s -> return (a, s)
+    {-# INLINE pure #-}
+    StateT mf <*> StateT mx = StateT $ \ s -> do
+        (f, s') <- mf s
+        (x, s'') <- mx s'
+        return (f x, s'')
+    {-# INLINE (<*>) #-}
+    m *> k = m >>= \_ -> k
+    {-# INLINE (*>) #-}
+
+instance (Functor m, MonadPlus m) => Alternative (StateT s m) where
+    empty = StateT $ \ _ -> mzero
+    {-# INLINE empty #-}
+    StateT m <|> StateT n = StateT $ \ s -> m s `mplus` n s
+    {-# INLINE (<|>) #-}
+
+instance (Monad m) => Monad (StateT s m) where
+#if !(MIN_VERSION_base(4,8,0))
+    return a = StateT $ \ s -> return (a, s)
+    {-# INLINE return #-}
+#endif
+    m >>= k  = StateT $ \ s -> do
+        (a, s') <- runStateT m s
+        runStateT (k a) s'
+    {-# INLINE (>>=) #-}
+#if !(MIN_VERSION_base(4,13,0))
+    fail str = StateT $ \ _ -> fail str
+    {-# INLINE fail #-}
+#endif
+
+#if MIN_VERSION_base(4,9,0)
+instance (Fail.MonadFail m) => Fail.MonadFail (StateT s m) where
+    fail str = StateT $ \ _ -> Fail.fail str
+    {-# INLINE fail #-}
+#endif
+
+instance (MonadPlus m) => MonadPlus (StateT s m) where
+    mzero       = StateT $ \ _ -> mzero
+    {-# INLINE mzero #-}
+    StateT m `mplus` StateT n = StateT $ \ s -> m s `mplus` n s
+    {-# INLINE mplus #-}
+
+instance (MonadFix m) => MonadFix (StateT s m) where
+    mfix f = StateT $ \ s -> mfix $ \ ~(a, _) -> runStateT (f a) s
+    {-# INLINE mfix #-}
+
+instance MonadTrans (StateT s) where
+    lift m = StateT $ \ s -> do
+        a <- m
+        return (a, s)
+    {-# INLINE lift #-}
+
+instance (MonadIO m) => MonadIO (StateT s m) where
+    liftIO = lift . liftIO
+    {-# INLINE liftIO #-}
+
+#if MIN_VERSION_base(4,12,0)
+instance Contravariant m => Contravariant (StateT s m) where
+    contramap f m = StateT $ \s ->
+      contramap (\ (a, s') -> (f a, s')) $ runStateT m s
+    {-# INLINE contramap #-}
+#endif
+
+-- | Fetch the current value of the state within the monad.
+get :: (Monad m) => StateT s m s
+get = state $ \ s -> (s, s)
+{-# INLINE get #-}
+
+-- | @'put' s@ sets the state within the monad to @s@.
+put :: (Monad m) => s -> StateT s m ()
+put s = state $ \ _ -> ((), s)
+{-# INLINE put #-}
+
+-- | @'modify' f@ is an action that updates the state to the result of
+-- applying @f@ to the current state.
+--
+-- * @'modify' f = 'get' >>= ('put' . f)@
+modify :: (Monad m) => (s -> s) -> StateT s m ()
+modify f = state $ \ s -> ((), f s)
+{-# INLINE modify #-}
+
+-- | A variant of 'modify' in which the computation is strict in the
+-- new state.
+--
+-- * @'modify'' f = 'get' >>= (('$!') 'put' . f)@
+modify' :: (Monad m) => (s -> s) -> StateT s m ()
+modify' f = do
+    s <- get
+    put $! f s
+{-# INLINE modify' #-}
+
+-- | Get a specific component of the state, using a projection function
+-- supplied.
+--
+-- * @'gets' f = 'liftM' f 'get'@
+gets :: (Monad m) => (s -> a) -> StateT s m a
+gets f = state $ \ s -> (f s, s)
+{-# INLINE gets #-}
+
+-- | Uniform lifting of a @callCC@ operation to the new monad.
+-- This version rolls back to the original state on entering the
+-- continuation.
+liftCallCC :: CallCC m (a,s) (b,s) -> CallCC (StateT s m) a b
+liftCallCC callCC f = StateT $ \ s ->
+    callCC $ \ c ->
+    runStateT (f (\ a -> StateT $ \ _ -> c (a, s))) s
+{-# INLINE liftCallCC #-}
+
+-- | In-situ lifting of a @callCC@ operation to the new monad.
+-- This version uses the current state on entering the continuation.
+-- It does not satisfy the uniformity property (see "Control.Monad.Signatures").
+liftCallCC' :: CallCC m (a,s) (b,s) -> CallCC (StateT s m) a b
+liftCallCC' callCC f = StateT $ \ s ->
+    callCC $ \ c ->
+    runStateT (f (\ a -> StateT $ \ s' -> c (a, s'))) s
+{-# INLINE liftCallCC' #-}
+
+-- | Lift a @catchE@ operation to the new monad.
+liftCatch :: Catch e m (a,s) -> Catch e (StateT s m) a
+liftCatch catchE m h =
+    StateT $ \ s -> runStateT m s `catchE` \ e -> runStateT (h e) s
+{-# INLINE liftCatch #-}
+
+-- | Lift a @listen@ operation to the new monad.
+liftListen :: (Monad m) => Listen w m (a,s) -> Listen w (StateT s m) a
+liftListen listen m = StateT $ \ s -> do
+    ((a, s'), w) <- listen (runStateT m s)
+    return ((a, w), s')
+{-# INLINE liftListen #-}
+
+-- | Lift a @pass@ operation to the new monad.
+liftPass :: (Monad m) => Pass w m (a,s) -> Pass w (StateT s m) a
+liftPass pass m = StateT $ \ s -> pass $ do
+    ((a, f), s') <- runStateT m s
+    return ((a, s'), f)
+{-# INLINE liftPass #-}
+
+{- $examples
+
+Parser from ParseLib with Hugs:
+
+> type Parser a = StateT String [] a
+>    ==> StateT (String -> [(a,String)])
+
+For example, item can be written as:
+
+> item = do (x:xs) <- get
+>        put xs
+>        return x
+>
+> type BoringState s a = StateT s Identity a
+>      ==> StateT (s -> Identity (a,s))
+>
+> type StateWithIO s a = StateT s IO a
+>      ==> StateT (s -> IO (a,s))
+>
+> type StateWithErr s a = StateT s Maybe a
+>      ==> StateT (s -> Maybe (a,s))
+
+-}
+
+{- $counting
+
+A function to increment a counter.
+Taken from the paper \"Generalising Monads to Arrows\",
+John Hughes (<http://www.cse.chalmers.se/~rjmh/>), November 1998:
+
+> tick :: State Int Int
+> tick = do n <- get
+>           put (n+1)
+>           return n
+
+Add one to the given number using the state monad:
+
+> plusOne :: Int -> Int
+> plusOne n = execState tick n
+
+A contrived addition example. Works only with positive numbers:
+
+> plus :: Int -> Int -> Int
+> plus n x = execState (sequence $ replicate n tick) x
+
+-}
+
+{- $labelling
+
+An example from /The Craft of Functional Programming/, Simon
+Thompson (<http://www.cs.kent.ac.uk/people/staff/sjt/>),
+Addison-Wesley 1999: \"Given an arbitrary tree, transform it to a
+tree of integers in which the original elements are replaced by
+natural numbers, starting from 0.  The same element has to be
+replaced by the same number at every occurrence, and when we meet
+an as-yet-unvisited element we have to find a \'new\' number to match
+it with:\"
+
+> data Tree a = Nil | Node a (Tree a) (Tree a) deriving (Show, Eq)
+> type Table a = [a]
+
+> numberTree :: Eq a => Tree a -> State (Table a) (Tree Int)
+> numberTree Nil = return Nil
+> numberTree (Node x t1 t2) = do
+>     num <- numberNode x
+>     nt1 <- numberTree t1
+>     nt2 <- numberTree t2
+>     return (Node num nt1 nt2)
+>   where
+>     numberNode :: Eq a => a -> State (Table a) Int
+>     numberNode x = do
+>         table <- get
+>         case elemIndex x table of
+>             Nothing -> do
+>                 put (table ++ [x])
+>                 return (length table)
+>             Just i -> return i
+
+numTree applies numberTree with an initial state:
+
+> numTree :: (Eq a) => Tree a -> Tree Int
+> numTree t = evalState (numberTree t) []
+
+> testTree = Node "Zero" (Node "One" (Node "Two" Nil Nil) (Node "One" (Node "Zero" Nil Nil) Nil)) Nil
+> numTree testTree => Node 0 (Node 1 (Node 2 Nil Nil) (Node 1 (Node 0 Nil Nil) Nil)) Nil
+
+-}

third_party/bazel/rules_haskell/examples/transformers/Control/Monad/Trans/Writer.hs

@@ -0,0 +1,25 @@
+{-# LANGUAGE CPP #-}
+#if __GLASGOW_HASKELL__ >= 702
+{-# LANGUAGE Safe #-}
+#endif
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Control.Monad.Trans.Writer
+-- Copyright   :  (c) Andy Gill 2001,
+--                (c) Oregon Graduate Institute of Science and Technology, 2001
+-- License     :  BSD-style (see the file LICENSE)
+--
+-- Maintainer  :  R.Paterson@city.ac.uk
+-- Stability   :  experimental
+-- Portability :  portable
+--
+-- The WriterT monad transformer.
+-- This version builds its output lazily; for a constant-space version
+-- with almost the same interface, see "Control.Monad.Trans.Writer.CPS".
+-----------------------------------------------------------------------------
+
+module Control.Monad.Trans.Writer (
+    module Control.Monad.Trans.Writer.Lazy
+  ) where
+
+import Control.Monad.Trans.Writer.Lazy

third_party/bazel/rules_haskell/examples/transformers/Control/Monad/Trans/Writer/CPS.hs

@@ -0,0 +1,283 @@
+{-# LANGUAGE CPP #-}
+#if __GLASGOW_HASKELL__ >= 702
+{-# LANGUAGE Safe #-}
+#endif
+#if __GLASGOW_HASKELL__ >= 710
+{-# LANGUAGE AutoDeriveTypeable #-}
+#endif
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Control.Monad.Trans.Writer.CPS
+-- Copyright   :  (c) Daniel Mendler 2016,
+--                (c) Andy Gill 2001,
+--                (c) Oregon Graduate Institute of Science and Technology, 2001
+-- License     :  BSD-style (see the file LICENSE)
+--
+-- Maintainer  :  R.Paterson@city.ac.uk
+-- Stability   :  experimental
+-- Portability :  portable
+--
+-- The strict 'WriterT' monad transformer, which adds collection of
+-- outputs (such as a count or string output) to a given monad.
+--
+-- This monad transformer provides only limited access to the output
+-- during the computation. For more general access, use
+-- "Control.Monad.Trans.State" instead.
+--
+-- This version builds its output strictly and uses continuation-passing-style
+-- to achieve constant space usage. This transformer can be used as a
+-- drop-in replacement for "Control.Monad.Trans.Writer.Strict".
+-----------------------------------------------------------------------------
+
+module Control.Monad.Trans.Writer.CPS (
+    -- * The Writer monad
+    Writer,
+    writer,
+    runWriter,
+    execWriter,
+    mapWriter,
+    -- * The WriterT monad transformer
+    WriterT,
+    writerT,
+    runWriterT,
+    execWriterT,
+    mapWriterT,
+    -- * Writer operations
+    tell,
+    listen,
+    listens,
+    pass,
+    censor,
+    -- * Lifting other operations
+    liftCallCC,
+    liftCatch,
+  ) where
+
+import Control.Applicative
+import Control.Monad
+import Control.Monad.Fix
+import Control.Monad.IO.Class
+import Control.Monad.Trans.Class
+import Control.Monad.Signatures
+import Data.Functor.Identity
+
+#if !(MIN_VERSION_base(4,8,0))
+import Data.Monoid
+#endif
+
+#if MIN_VERSION_base(4,9,0)
+import qualified Control.Monad.Fail as Fail
+#endif
+
+-- ---------------------------------------------------------------------------
+-- | A writer monad parameterized by the type @w@ of output to accumulate.
+--
+-- The 'return' function produces the output 'mempty', while '>>='
+-- combines the outputs of the subcomputations using 'mappend'.
+type Writer w = WriterT w Identity
+
+-- | Construct a writer computation from a (result, output) pair.
+-- (The inverse of 'runWriter'.)
+writer :: (Monoid w, Monad m) => (a, w) -> WriterT w m a
+writer (a, w') = WriterT $ \ w ->
+    let wt = w `mappend` w' in wt `seq` return (a, wt)
+{-# INLINE writer #-}
+
+-- | Unwrap a writer computation as a (result, output) pair.
+-- (The inverse of 'writer'.)
+runWriter :: (Monoid w) => Writer w a -> (a, w)
+runWriter = runIdentity . runWriterT
+{-# INLINE runWriter #-}
+
+-- | Extract the output from a writer computation.
+--
+-- * @'execWriter' m = 'snd' ('runWriter' m)@
+execWriter :: (Monoid w) => Writer w a -> w
+execWriter = runIdentity . execWriterT
+{-# INLINE execWriter #-}
+
+-- | Map both the return value and output of a computation using
+-- the given function.
+--
+-- * @'runWriter' ('mapWriter' f m) = f ('runWriter' m)@
+mapWriter :: (Monoid w, Monoid w') =>
+    ((a, w) -> (b, w')) -> Writer w a -> Writer w' b
+mapWriter f = mapWriterT (Identity . f . runIdentity)
+{-# INLINE mapWriter #-}
+
+-- ---------------------------------------------------------------------------
+-- | A writer monad parameterized by:
+--
+--   * @w@ - the output to accumulate.
+--
+--   * @m@ - The inner monad.
+--
+-- The 'return' function produces the output 'mempty', while '>>='
+-- combines the outputs of the subcomputations using 'mappend'.
+
+newtype WriterT w m a = WriterT { unWriterT :: w -> m (a, w) }
+
+-- | Construct a writer computation from a (result, output) computation.
+-- (The inverse of 'runWriterT'.)
+writerT :: (Functor m, Monoid w) => m (a, w) -> WriterT w m a
+writerT f = WriterT $ \ w ->
+    (\ (a, w') -> let wt = w `mappend` w' in wt `seq` (a, wt)) <$> f
+{-# INLINE writerT #-}
+
+-- | Unwrap a writer computation.
+-- (The inverse of 'writerT'.)
+runWriterT :: (Monoid w) => WriterT w m a -> m (a, w)
+runWriterT m = unWriterT m mempty
+{-# INLINE runWriterT #-}
+
+-- | Extract the output from a writer computation.
+--
+-- * @'execWriterT' m = 'liftM' 'snd' ('runWriterT' m)@
+execWriterT :: (Monad m, Monoid w) => WriterT w m a -> m w
+execWriterT m = do
+    (_, w) <- runWriterT m
+    return w
+{-# INLINE execWriterT #-}
+
+-- | Map both the return value and output of a computation using
+-- the given function.
+--
+-- * @'runWriterT' ('mapWriterT' f m) = f ('runWriterT' m)@
+mapWriterT :: (Monad n, Monoid w, Monoid w') =>
+    (m (a, w) -> n (b, w')) -> WriterT w m a -> WriterT w' n b
+mapWriterT f m = WriterT $ \ w -> do
+    (a, w') <- f (runWriterT m)
+    let wt = w `mappend` w'
+    wt `seq` return (a, wt)
+{-# INLINE mapWriterT #-}
+
+instance (Functor m) => Functor (WriterT w m) where
+    fmap f m = WriterT $ \ w -> (\ (a, w') -> (f a, w')) <$> unWriterT m w
+    {-# INLINE fmap #-}
+
+instance (Functor m, Monad m) => Applicative (WriterT w m) where
+    pure a = WriterT $ \ w -> return (a, w)
+    {-# INLINE pure #-}
+
+    WriterT mf <*> WriterT mx = WriterT $ \ w -> do
+        (f, w') <- mf w
+        (x, w'') <- mx w'
+        return (f x, w'')
+    {-# INLINE (<*>) #-}
+
+instance (Functor m, MonadPlus m) => Alternative (WriterT w m) where
+    empty = WriterT $ const mzero
+    {-# INLINE empty #-}
+
+    WriterT m <|> WriterT n = WriterT $ \ w -> m w `mplus` n w
+    {-# INLINE (<|>) #-}
+
+instance (Monad m) => Monad (WriterT w m) where
+#if !(MIN_VERSION_base(4,8,0))
+    return a = WriterT $ \ w -> return (a, w)
+    {-# INLINE return #-}
+#endif
+
+    m >>= k = WriterT $ \ w -> do
+        (a, w') <- unWriterT m w
+        unWriterT (k a) w'
+    {-# INLINE (>>=) #-}
+
+#if !(MIN_VERSION_base(4,13,0))
+    fail msg = WriterT $ \ _ -> fail msg
+    {-# INLINE fail #-}
+#endif
+
+#if MIN_VERSION_base(4,9,0)
+instance (Fail.MonadFail m) => Fail.MonadFail (WriterT w m) where
+    fail msg = WriterT $ \ _ -> Fail.fail msg
+    {-# INLINE fail #-}
+#endif
+
+instance (Functor m, MonadPlus m) => MonadPlus (WriterT w m) where
+    mzero = empty
+    {-# INLINE mzero #-}
+    mplus = (<|>)
+    {-# INLINE mplus #-}
+
+instance (MonadFix m) => MonadFix (WriterT w m) where
+    mfix f = WriterT $ \ w -> mfix $ \ ~(a, _) -> unWriterT (f a) w
+    {-# INLINE mfix #-}
+
+instance MonadTrans (WriterT w) where
+    lift m = WriterT $ \ w -> do
+        a <- m
+        return (a, w)
+    {-# INLINE lift #-}
+
+instance (MonadIO m) => MonadIO (WriterT w m) where
+    liftIO = lift . liftIO
+    {-# INLINE liftIO #-}
+
+-- | @'tell' w@ is an action that produces the output @w@.
+tell :: (Monoid w, Monad m) => w -> WriterT w m ()
+tell w = writer ((), w)
+{-# INLINE tell #-}
+
+-- | @'listen' m@ is an action that executes the action @m@ and adds its
+-- output to the value of the computation.
+--
+-- * @'runWriterT' ('listen' m) = 'liftM' (\\ (a, w) -> ((a, w), w)) ('runWriterT' m)@
+listen :: (Monoid w, Monad m) => WriterT w m a -> WriterT w m (a, w)
+listen = listens id
+{-# INLINE listen #-}
+
+-- | @'listens' f m@ is an action that executes the action @m@ and adds
+-- the result of applying @f@ to the output to the value of the computation.
+--
+-- * @'listens' f m = 'liftM' (id *** f) ('listen' m)@
+--
+-- * @'runWriterT' ('listens' f m) = 'liftM' (\\ (a, w) -> ((a, f w), w)) ('runWriterT' m)@
+listens :: (Monoid w, Monad m) =>
+    (w -> b) -> WriterT w m a -> WriterT w m (a, b)
+listens f m = WriterT $ \ w -> do
+    (a, w') <- runWriterT m
+    let wt = w `mappend` w'
+    wt `seq` return ((a, f w'), wt)
+{-# INLINE listens #-}
+
+-- | @'pass' m@ is an action that executes the action @m@, which returns
+-- a value and a function, and returns the value, applying the function
+-- to the output.
+--
+-- * @'runWriterT' ('pass' m) = 'liftM' (\\ ((a, f), w) -> (a, f w)) ('runWriterT' m)@
+pass :: (Monoid w, Monoid w', Monad m) =>
+    WriterT w m (a, w -> w') -> WriterT w' m a
+pass m = WriterT $ \ w -> do
+    ((a, f), w') <- runWriterT m
+    let wt = w `mappend` f w'
+    wt `seq` return (a, wt)
+{-# INLINE pass #-}
+
+-- | @'censor' f m@ is an action that executes the action @m@ and
+-- applies the function @f@ to its output, leaving the return value
+-- unchanged.
+--
+-- * @'censor' f m = 'pass' ('liftM' (\\ x -> (x,f)) m)@
+--
+-- * @'runWriterT' ('censor' f m) = 'liftM' (\\ (a, w) -> (a, f w)) ('runWriterT' m)@
+censor :: (Monoid w, Monad m) => (w -> w) -> WriterT w m a -> WriterT w m a
+censor f m = WriterT $ \ w -> do
+    (a, w') <- runWriterT m
+    let wt = w `mappend` f w'
+    wt `seq` return (a, wt)
+{-# INLINE censor #-}
+
+-- | Uniform lifting of a @callCC@ operation to the new monad.
+-- This version rolls back to the original state on entering the
+-- continuation.
+liftCallCC :: CallCC m (a, w) (b, w) -> CallCC (WriterT w m) a b
+liftCallCC callCC f = WriterT $ \ w ->
+    callCC $ \ c -> unWriterT (f (\ a -> WriterT $ \ _ -> c (a, w))) w
+{-# INLINE liftCallCC #-}
+
+-- | Lift a @catchE@ operation to the new monad.
+liftCatch :: Catch e m (a, w) -> Catch e (WriterT w m) a
+liftCatch catchE m h = WriterT $ \ w ->
+    unWriterT m w `catchE` \ e -> unWriterT (h e) w
+{-# INLINE liftCatch #-}

third_party/bazel/rules_haskell/examples/transformers/Control/Monad/Trans/Writer/Lazy.hs

@@ -0,0 +1,313 @@
+{-# LANGUAGE CPP #-}
+#if __GLASGOW_HASKELL__ >= 702
+{-# LANGUAGE Safe #-}
+#endif
+#if __GLASGOW_HASKELL__ >= 710
+{-# LANGUAGE AutoDeriveTypeable #-}
+#endif
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Control.Monad.Trans.Writer.Lazy
+-- Copyright   :  (c) Andy Gill 2001,
+--                (c) Oregon Graduate Institute of Science and Technology, 2001
+-- License     :  BSD-style (see the file LICENSE)
+--
+-- Maintainer  :  R.Paterson@city.ac.uk
+-- Stability   :  experimental
+-- Portability :  portable
+--
+-- The lazy 'WriterT' monad transformer, which adds collection of
+-- outputs (such as a count or string output) to a given monad.
+--
+-- This monad transformer provides only limited access to the output
+-- during the computation.  For more general access, use
+-- "Control.Monad.Trans.State" instead.
+--
+-- This version builds its output lazily; for a constant-space version
+-- with almost the same interface, see "Control.Monad.Trans.Writer.CPS".
+-----------------------------------------------------------------------------
+
+module Control.Monad.Trans.Writer.Lazy (
+    -- * The Writer monad
+    Writer,
+    writer,
+    runWriter,
+    execWriter,
+    mapWriter,
+    -- * The WriterT monad transformer
+    WriterT(..),
+    execWriterT,
+    mapWriterT,
+    -- * Writer operations
+    tell,
+    listen,
+    listens,
+    pass,
+    censor,
+    -- * Lifting other operations
+    liftCallCC,
+    liftCatch,
+  ) where
+
+import Control.Monad.IO.Class
+import Control.Monad.Trans.Class
+import Data.Functor.Classes
+#if MIN_VERSION_base(4,12,0)
+import Data.Functor.Contravariant
+#endif
+import Data.Functor.Identity
+
+import Control.Applicative
+import Control.Monad
+#if MIN_VERSION_base(4,9,0)
+import qualified Control.Monad.Fail as Fail
+#endif
+import Control.Monad.Fix
+import Control.Monad.Signatures
+#if MIN_VERSION_base(4,4,0)
+import Control.Monad.Zip (MonadZip(mzipWith))
+#endif
+import Data.Foldable
+import Data.Monoid
+import Data.Traversable (Traversable(traverse))
+import Prelude hiding (null, length)
+
+-- ---------------------------------------------------------------------------
+-- | A writer monad parameterized by the type @w@ of output to accumulate.
+--
+-- The 'return' function produces the output 'mempty', while @>>=@
+-- combines the outputs of the subcomputations using 'mappend'.
+type Writer w = WriterT w Identity
+
+-- | Construct a writer computation from a (result, output) pair.
+-- (The inverse of 'runWriter'.)
+writer :: (Monad m) => (a, w) -> WriterT w m a
+writer = WriterT . return
+{-# INLINE writer #-}
+
+-- | Unwrap a writer computation as a (result, output) pair.
+-- (The inverse of 'writer'.)
+runWriter :: Writer w a -> (a, w)
+runWriter = runIdentity . runWriterT
+{-# INLINE runWriter #-}
+
+-- | Extract the output from a writer computation.
+--
+-- * @'execWriter' m = 'snd' ('runWriter' m)@
+execWriter :: Writer w a -> w
+execWriter m = snd (runWriter m)
+{-# INLINE execWriter #-}
+
+-- | Map both the return value and output of a computation using
+-- the given function.
+--
+-- * @'runWriter' ('mapWriter' f m) = f ('runWriter' m)@
+mapWriter :: ((a, w) -> (b, w')) -> Writer w a -> Writer w' b
+mapWriter f = mapWriterT (Identity . f . runIdentity)
+{-# INLINE mapWriter #-}
+
+-- ---------------------------------------------------------------------------
+-- | A writer monad parameterized by:
+--
+--   * @w@ - the output to accumulate.
+--
+--   * @m@ - The inner monad.
+--
+-- The 'return' function produces the output 'mempty', while @>>=@
+-- combines the outputs of the subcomputations using 'mappend'.
+newtype WriterT w m a = WriterT { runWriterT :: m (a, w) }
+
+instance (Eq w, Eq1 m) => Eq1 (WriterT w m) where
+    liftEq eq (WriterT m1) (WriterT m2) = liftEq (liftEq2 eq (==)) m1 m2
+    {-# INLINE liftEq #-}
+
+instance (Ord w, Ord1 m) => Ord1 (WriterT w m) where
+    liftCompare comp (WriterT m1) (WriterT m2) =
+        liftCompare (liftCompare2 comp compare) m1 m2
+    {-# INLINE liftCompare #-}
+
+instance (Read w, Read1 m) => Read1 (WriterT w m) where
+    liftReadsPrec rp rl = readsData $
+        readsUnaryWith (liftReadsPrec rp' rl') "WriterT" WriterT
+      where
+        rp' = liftReadsPrec2 rp rl readsPrec readList
+        rl' = liftReadList2 rp rl readsPrec readList
+
+instance (Show w, Show1 m) => Show1 (WriterT w m) where
+    liftShowsPrec sp sl d (WriterT m) =
+        showsUnaryWith (liftShowsPrec sp' sl') "WriterT" d m
+      where
+        sp' = liftShowsPrec2 sp sl showsPrec showList
+        sl' = liftShowList2 sp sl showsPrec showList
+
+instance (Eq w, Eq1 m, Eq a) => Eq (WriterT w m a) where (==) = eq1
+instance (Ord w, Ord1 m, Ord a) => Ord (WriterT w m a) where compare = compare1
+instance (Read w, Read1 m, Read a) => Read (WriterT w m a) where
+    readsPrec = readsPrec1
+instance (Show w, Show1 m, Show a) => Show (WriterT w m a) where
+    showsPrec = showsPrec1
+
+-- | Extract the output from a writer computation.
+--
+-- * @'execWriterT' m = 'liftM' 'snd' ('runWriterT' m)@
+execWriterT :: (Monad m) => WriterT w m a -> m w
+execWriterT m = do
+    ~(_, w) <- runWriterT m
+    return w
+{-# INLINE execWriterT #-}
+
+-- | Map both the return value and output of a computation using
+-- the given function.
+--
+-- * @'runWriterT' ('mapWriterT' f m) = f ('runWriterT' m)@
+mapWriterT :: (m (a, w) -> n (b, w')) -> WriterT w m a -> WriterT w' n b
+mapWriterT f m = WriterT $ f (runWriterT m)
+{-# INLINE mapWriterT #-}
+
+instance (Functor m) => Functor (WriterT w m) where
+    fmap f = mapWriterT $ fmap $ \ ~(a, w) -> (f a, w)
+    {-# INLINE fmap #-}
+
+instance (Foldable f) => Foldable (WriterT w f) where
+    foldMap f = foldMap (f . fst) . runWriterT
+    {-# INLINE foldMap #-}
+#if MIN_VERSION_base(4,8,0)
+    null (WriterT t) = null t
+    length (WriterT t) = length t
+#endif
+
+instance (Traversable f) => Traversable (WriterT w f) where
+    traverse f = fmap WriterT . traverse f' . runWriterT where
+       f' (a, b) = fmap (\ c -> (c, b)) (f a)
+    {-# INLINE traverse #-}
+
+instance (Monoid w, Applicative m) => Applicative (WriterT w m) where
+    pure a  = WriterT $ pure (a, mempty)
+    {-# INLINE pure #-}
+    f <*> v = WriterT $ liftA2 k (runWriterT f) (runWriterT v)
+      where k ~(a, w) ~(b, w') = (a b, w `mappend` w')
+    {-# INLINE (<*>) #-}
+
+instance (Monoid w, Alternative m) => Alternative (WriterT w m) where
+    empty   = WriterT empty
+    {-# INLINE empty #-}
+    m <|> n = WriterT $ runWriterT m <|> runWriterT n
+    {-# INLINE (<|>) #-}
+
+instance (Monoid w, Monad m) => Monad (WriterT w m) where
+#if !(MIN_VERSION_base(4,8,0))
+    return a = writer (a, mempty)
+    {-# INLINE return #-}
+#endif
+    m >>= k  = WriterT $ do
+        ~(a, w)  <- runWriterT m
+        ~(b, w') <- runWriterT (k a)
+        return (b, w `mappend` w')
+    {-# INLINE (>>=) #-}
+#if !(MIN_VERSION_base(4,13,0))
+    fail msg = WriterT $ fail msg
+    {-# INLINE fail #-}
+#endif
+
+#if MIN_VERSION_base(4,9,0)
+instance (Monoid w, Fail.MonadFail m) => Fail.MonadFail (WriterT w m) where
+    fail msg = WriterT $ Fail.fail msg
+    {-# INLINE fail #-}
+#endif
+
+instance (Monoid w, MonadPlus m) => MonadPlus (WriterT w m) where
+    mzero       = WriterT mzero
+    {-# INLINE mzero #-}
+    m `mplus` n = WriterT $ runWriterT m `mplus` runWriterT n
+    {-# INLINE mplus #-}
+
+instance (Monoid w, MonadFix m) => MonadFix (WriterT w m) where
+    mfix m = WriterT $ mfix $ \ ~(a, _) -> runWriterT (m a)
+    {-# INLINE mfix #-}
+
+instance (Monoid w) => MonadTrans (WriterT w) where
+    lift m = WriterT $ do
+        a <- m
+        return (a, mempty)
+    {-# INLINE lift #-}
+
+instance (Monoid w, MonadIO m) => MonadIO (WriterT w m) where
+    liftIO = lift . liftIO
+    {-# INLINE liftIO #-}
+
+#if MIN_VERSION_base(4,4,0)
+instance (Monoid w, MonadZip m) => MonadZip (WriterT w m) where
+    mzipWith f (WriterT x) (WriterT y) = WriterT $
+        mzipWith (\ ~(a, w) ~(b, w') -> (f a b, w `mappend` w')) x y
+    {-# INLINE mzipWith #-}
+#endif
+
+#if MIN_VERSION_base(4,12,0)
+instance Contravariant m => Contravariant (WriterT w m) where
+    contramap f = mapWriterT $ contramap $ \ ~(a, w) -> (f a, w)
+    {-# INLINE contramap #-}
+#endif
+
+-- | @'tell' w@ is an action that produces the output @w@.
+tell :: (Monad m) => w -> WriterT w m ()
+tell w = writer ((), w)
+{-# INLINE tell #-}
+
+-- | @'listen' m@ is an action that executes the action @m@ and adds its
+-- output to the value of the computation.
+--
+-- * @'runWriterT' ('listen' m) = 'liftM' (\\ (a, w) -> ((a, w), w)) ('runWriterT' m)@
+listen :: (Monad m) => WriterT w m a -> WriterT w m (a, w)
+listen m = WriterT $ do
+    ~(a, w) <- runWriterT m
+    return ((a, w), w)
+{-# INLINE listen #-}
+
+-- | @'listens' f m@ is an action that executes the action @m@ and adds
+-- the result of applying @f@ to the output to the value of the computation.
+--
+-- * @'listens' f m = 'liftM' (id *** f) ('listen' m)@
+--
+-- * @'runWriterT' ('listens' f m) = 'liftM' (\\ (a, w) -> ((a, f w), w)) ('runWriterT' m)@
+listens :: (Monad m) => (w -> b) -> WriterT w m a -> WriterT w m (a, b)
+listens f m = WriterT $ do
+    ~(a, w) <- runWriterT m
+    return ((a, f w), w)
+{-# INLINE listens #-}
+
+-- | @'pass' m@ is an action that executes the action @m@, which returns
+-- a value and a function, and returns the value, applying the function
+-- to the output.
+--
+-- * @'runWriterT' ('pass' m) = 'liftM' (\\ ((a, f), w) -> (a, f w)) ('runWriterT' m)@
+pass :: (Monad m) => WriterT w m (a, w -> w) -> WriterT w m a
+pass m = WriterT $ do
+    ~((a, f), w) <- runWriterT m
+    return (a, f w)
+{-# INLINE pass #-}
+
+-- | @'censor' f m@ is an action that executes the action @m@ and
+-- applies the function @f@ to its output, leaving the return value
+-- unchanged.
+--
+-- * @'censor' f m = 'pass' ('liftM' (\\ x -> (x,f)) m)@
+--
+-- * @'runWriterT' ('censor' f m) = 'liftM' (\\ (a, w) -> (a, f w)) ('runWriterT' m)@
+censor :: (Monad m) => (w -> w) -> WriterT w m a -> WriterT w m a
+censor f m = WriterT $ do
+    ~(a, w) <- runWriterT m
+    return (a, f w)
+{-# INLINE censor #-}
+
+-- | Lift a @callCC@ operation to the new monad.
+liftCallCC :: (Monoid w) => CallCC m (a,w) (b,w) -> CallCC (WriterT w m) a b
+liftCallCC callCC f = WriterT $
+    callCC $ \ c ->
+    runWriterT (f (\ a -> WriterT $ c (a, mempty)))
+{-# INLINE liftCallCC #-}
+
+-- | Lift a @catchE@ operation to the new monad.
+liftCatch :: Catch e m (a,w) -> Catch e (WriterT w m) a
+liftCatch catchE m h =
+    WriterT $ runWriterT m `catchE` \ e -> runWriterT (h e)
+{-# INLINE liftCatch #-}

third_party/bazel/rules_haskell/examples/transformers/Control/Monad/Trans/Writer/Strict.hs

@@ -0,0 +1,316 @@
+{-# LANGUAGE CPP #-}
+#if __GLASGOW_HASKELL__ >= 702
+{-# LANGUAGE Safe #-}
+#endif
+#if __GLASGOW_HASKELL__ >= 710
+{-# LANGUAGE AutoDeriveTypeable #-}
+#endif
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Control.Monad.Trans.Writer.Strict
+-- Copyright   :  (c) Andy Gill 2001,
+--                (c) Oregon Graduate Institute of Science and Technology, 2001
+-- License     :  BSD-style (see the file LICENSE)
+--
+-- Maintainer  :  R.Paterson@city.ac.uk
+-- Stability   :  experimental
+-- Portability :  portable
+--
+-- The strict 'WriterT' monad transformer, which adds collection of
+-- outputs (such as a count or string output) to a given monad.
+--
+-- This monad transformer provides only limited access to the output
+-- during the computation.  For more general access, use
+-- "Control.Monad.Trans.State" instead.
+--
+-- This version builds its output strictly; for a lazy version with
+-- the same interface, see "Control.Monad.Trans.Writer.Lazy".
+-- Although the output is built strictly, it is not possible to
+-- achieve constant space behaviour with this transformer: for that,
+-- use "Control.Monad.Trans.Writer.CPS" instead.
+-----------------------------------------------------------------------------
+
+module Control.Monad.Trans.Writer.Strict (
+    -- * The Writer monad
+    Writer,
+    writer,
+    runWriter,
+    execWriter,
+    mapWriter,
+    -- * The WriterT monad transformer
+    WriterT(..),
+    execWriterT,
+    mapWriterT,
+    -- * Writer operations
+    tell,
+    listen,
+    listens,
+    pass,
+    censor,
+    -- * Lifting other operations
+    liftCallCC,
+    liftCatch,
+  ) where
+
+import Control.Monad.IO.Class
+import Control.Monad.Trans.Class
+import Data.Functor.Classes
+#if MIN_VERSION_base(4,12,0)
+import Data.Functor.Contravariant
+#endif
+import Data.Functor.Identity
+
+import Control.Applicative
+import Control.Monad
+#if MIN_VERSION_base(4,9,0)
+import qualified Control.Monad.Fail as Fail
+#endif
+import Control.Monad.Fix
+import Control.Monad.Signatures
+#if MIN_VERSION_base(4,4,0)
+import Control.Monad.Zip (MonadZip(mzipWith))
+#endif
+import Data.Foldable
+import Data.Monoid
+import Data.Traversable (Traversable(traverse))
+import Prelude hiding (null, length)
+
+-- ---------------------------------------------------------------------------
+-- | A writer monad parameterized by the type @w@ of output to accumulate.
+--
+-- The 'return' function produces the output 'mempty', while @>>=@
+-- combines the outputs of the subcomputations using 'mappend'.
+type Writer w = WriterT w Identity
+
+-- | Construct a writer computation from a (result, output) pair.
+-- (The inverse of 'runWriter'.)
+writer :: (Monad m) => (a, w) -> WriterT w m a
+writer = WriterT . return
+{-# INLINE writer #-}
+
+-- | Unwrap a writer computation as a (result, output) pair.
+-- (The inverse of 'writer'.)
+runWriter :: Writer w a -> (a, w)
+runWriter = runIdentity . runWriterT
+{-# INLINE runWriter #-}
+
+-- | Extract the output from a writer computation.
+--
+-- * @'execWriter' m = 'snd' ('runWriter' m)@
+execWriter :: Writer w a -> w
+execWriter m = snd (runWriter m)
+{-# INLINE execWriter #-}
+
+-- | Map both the return value and output of a computation using
+-- the given function.
+--
+-- * @'runWriter' ('mapWriter' f m) = f ('runWriter' m)@
+mapWriter :: ((a, w) -> (b, w')) -> Writer w a -> Writer w' b
+mapWriter f = mapWriterT (Identity . f . runIdentity)
+{-# INLINE mapWriter #-}
+
+-- ---------------------------------------------------------------------------
+-- | A writer monad parameterized by:
+--
+--   * @w@ - the output to accumulate.
+--
+--   * @m@ - The inner monad.
+--
+-- The 'return' function produces the output 'mempty', while @>>=@
+-- combines the outputs of the subcomputations using 'mappend'.
+newtype WriterT w m a = WriterT { runWriterT :: m (a, w) }
+
+instance (Eq w, Eq1 m) => Eq1 (WriterT w m) where
+    liftEq eq (WriterT m1) (WriterT m2) = liftEq (liftEq2 eq (==)) m1 m2
+    {-# INLINE liftEq #-}
+
+instance (Ord w, Ord1 m) => Ord1 (WriterT w m) where
+    liftCompare comp (WriterT m1) (WriterT m2) =
+        liftCompare (liftCompare2 comp compare) m1 m2
+    {-# INLINE liftCompare #-}
+
+instance (Read w, Read1 m) => Read1 (WriterT w m) where
+    liftReadsPrec rp rl = readsData $
+        readsUnaryWith (liftReadsPrec rp' rl') "WriterT" WriterT
+      where
+        rp' = liftReadsPrec2 rp rl readsPrec readList
+        rl' = liftReadList2 rp rl readsPrec readList
+
+instance (Show w, Show1 m) => Show1 (WriterT w m) where
+    liftShowsPrec sp sl d (WriterT m) =
+        showsUnaryWith (liftShowsPrec sp' sl') "WriterT" d m
+      where
+        sp' = liftShowsPrec2 sp sl showsPrec showList
+        sl' = liftShowList2 sp sl showsPrec showList
+
+instance (Eq w, Eq1 m, Eq a) => Eq (WriterT w m a) where (==) = eq1
+instance (Ord w, Ord1 m, Ord a) => Ord (WriterT w m a) where compare = compare1
+instance (Read w, Read1 m, Read a) => Read (WriterT w m a) where
+    readsPrec = readsPrec1
+instance (Show w, Show1 m, Show a) => Show (WriterT w m a) where
+    showsPrec = showsPrec1
+
+-- | Extract the output from a writer computation.
+--
+-- * @'execWriterT' m = 'liftM' 'snd' ('runWriterT' m)@
+execWriterT :: (Monad m) => WriterT w m a -> m w
+execWriterT m = do
+    (_, w) <- runWriterT m
+    return w
+{-# INLINE execWriterT #-}
+
+-- | Map both the return value and output of a computation using
+-- the given function.
+--
+-- * @'runWriterT' ('mapWriterT' f m) = f ('runWriterT' m)@
+mapWriterT :: (m (a, w) -> n (b, w')) -> WriterT w m a -> WriterT w' n b
+mapWriterT f m = WriterT $ f (runWriterT m)
+{-# INLINE mapWriterT #-}
+
+instance (Functor m) => Functor (WriterT w m) where
+    fmap f = mapWriterT $ fmap $ \ (a, w) -> (f a, w)
+    {-# INLINE fmap #-}
+
+instance (Foldable f) => Foldable (WriterT w f) where
+    foldMap f = foldMap (f . fst) . runWriterT
+    {-# INLINE foldMap #-}
+#if MIN_VERSION_base(4,8,0)
+    null (WriterT t) = null t
+    length (WriterT t) = length t
+#endif
+
+instance (Traversable f) => Traversable (WriterT w f) where
+    traverse f = fmap WriterT . traverse f' . runWriterT where
+       f' (a, b) = fmap (\ c -> (c, b)) (f a)
+    {-# INLINE traverse #-}
+
+instance (Monoid w, Applicative m) => Applicative (WriterT w m) where
+    pure a  = WriterT $ pure (a, mempty)
+    {-# INLINE pure #-}
+    f <*> v = WriterT $ liftA2 k (runWriterT f) (runWriterT v)
+      where k (a, w) (b, w') = (a b, w `mappend` w')
+    {-# INLINE (<*>) #-}
+
+instance (Monoid w, Alternative m) => Alternative (WriterT w m) where
+    empty   = WriterT empty
+    {-# INLINE empty #-}
+    m <|> n = WriterT $ runWriterT m <|> runWriterT n
+    {-# INLINE (<|>) #-}
+
+instance (Monoid w, Monad m) => Monad (WriterT w m) where
+#if !(MIN_VERSION_base(4,8,0))
+    return a = writer (a, mempty)
+    {-# INLINE return #-}
+#endif
+    m >>= k  = WriterT $ do
+        (a, w)  <- runWriterT m
+        (b, w') <- runWriterT (k a)
+        return (b, w `mappend` w')
+    {-# INLINE (>>=) #-}
+#if !(MIN_VERSION_base(4,13,0))
+    fail msg = WriterT $ fail msg
+    {-# INLINE fail #-}
+#endif
+
+#if MIN_VERSION_base(4,9,0)
+instance (Monoid w, Fail.MonadFail m) => Fail.MonadFail (WriterT w m) where
+    fail msg = WriterT $ Fail.fail msg
+    {-# INLINE fail #-}
+#endif
+
+instance (Monoid w, MonadPlus m) => MonadPlus (WriterT w m) where
+    mzero       = WriterT mzero
+    {-# INLINE mzero #-}
+    m `mplus` n = WriterT $ runWriterT m `mplus` runWriterT n
+    {-# INLINE mplus #-}
+
+instance (Monoid w, MonadFix m) => MonadFix (WriterT w m) where
+    mfix m = WriterT $ mfix $ \ ~(a, _) -> runWriterT (m a)
+    {-# INLINE mfix #-}
+
+instance (Monoid w) => MonadTrans (WriterT w) where
+    lift m = WriterT $ do
+        a <- m
+        return (a, mempty)
+    {-# INLINE lift #-}
+
+instance (Monoid w, MonadIO m) => MonadIO (WriterT w m) where
+    liftIO = lift . liftIO
+    {-# INLINE liftIO #-}
+
+#if MIN_VERSION_base(4,4,0)
+instance (Monoid w, MonadZip m) => MonadZip (WriterT w m) where
+    mzipWith f (WriterT x) (WriterT y) = WriterT $
+        mzipWith (\ (a, w) (b, w') -> (f a b, w `mappend` w')) x y
+    {-# INLINE mzipWith #-}
+#endif
+
+#if MIN_VERSION_base(4,12,0)
+instance Contravariant m => Contravariant (WriterT w m) where
+    contramap f = mapWriterT $ contramap $ \ (a, w) -> (f a, w)
+    {-# INLINE contramap #-}
+#endif
+
+-- | @'tell' w@ is an action that produces the output @w@.
+tell :: (Monad m) => w -> WriterT w m ()
+tell w = writer ((), w)
+{-# INLINE tell #-}
+
+-- | @'listen' m@ is an action that executes the action @m@ and adds its
+-- output to the value of the computation.
+--
+-- * @'runWriterT' ('listen' m) = 'liftM' (\\ (a, w) -> ((a, w), w)) ('runWriterT' m)@
+listen :: (Monad m) => WriterT w m a -> WriterT w m (a, w)
+listen m = WriterT $ do
+    (a, w) <- runWriterT m
+    return ((a, w), w)
+{-# INLINE listen #-}
+
+-- | @'listens' f m@ is an action that executes the action @m@ and adds
+-- the result of applying @f@ to the output to the value of the computation.
+--
+-- * @'listens' f m = 'liftM' (id *** f) ('listen' m)@
+--
+-- * @'runWriterT' ('listens' f m) = 'liftM' (\\ (a, w) -> ((a, f w), w)) ('runWriterT' m)@
+listens :: (Monad m) => (w -> b) -> WriterT w m a -> WriterT w m (a, b)
+listens f m = WriterT $ do
+    (a, w) <- runWriterT m
+    return ((a, f w), w)
+{-# INLINE listens #-}
+
+-- | @'pass' m@ is an action that executes the action @m@, which returns
+-- a value and a function, and returns the value, applying the function
+-- to the output.
+--
+-- * @'runWriterT' ('pass' m) = 'liftM' (\\ ((a, f), w) -> (a, f w)) ('runWriterT' m)@
+pass :: (Monad m) => WriterT w m (a, w -> w) -> WriterT w m a
+pass m = WriterT $ do
+    ((a, f), w) <- runWriterT m
+    return (a, f w)
+{-# INLINE pass #-}
+
+-- | @'censor' f m@ is an action that executes the action @m@ and
+-- applies the function @f@ to its output, leaving the return value
+-- unchanged.
+--
+-- * @'censor' f m = 'pass' ('liftM' (\\ x -> (x,f)) m)@
+--
+-- * @'runWriterT' ('censor' f m) = 'liftM' (\\ (a, w) -> (a, f w)) ('runWriterT' m)@
+censor :: (Monad m) => (w -> w) -> WriterT w m a -> WriterT w m a
+censor f m = WriterT $ do
+    (a, w) <- runWriterT m
+    return (a, f w)
+{-# INLINE censor #-}
+
+-- | Lift a @callCC@ operation to the new monad.
+liftCallCC :: (Monoid w) => CallCC m (a,w) (b,w) -> CallCC (WriterT w m) a b
+liftCallCC callCC f = WriterT $
+    callCC $ \ c ->
+    runWriterT (f (\ a -> WriterT $ c (a, mempty)))
+{-# INLINE liftCallCC #-}
+
+-- | Lift a @catchE@ operation to the new monad.
+liftCatch :: Catch e m (a,w) -> Catch e (WriterT w m) a
+liftCatch catchE m h =
+    WriterT $ runWriterT m `catchE` \ e -> runWriterT (h e)
+{-# INLINE liftCatch #-}

third_party/bazel/rules_haskell/examples/transformers/Data/Functor/Constant.hs

@@ -0,0 +1,152 @@
+{-# LANGUAGE CPP #-}
+#if __GLASGOW_HASKELL__ >= 702
+{-# LANGUAGE Safe #-}
+#endif
+#if __GLASGOW_HASKELL__ >= 706
+{-# LANGUAGE PolyKinds #-}
+#endif
+#if __GLASGOW_HASKELL__ >= 710
+{-# LANGUAGE AutoDeriveTypeable #-}
+#endif
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Data.Functor.Constant
+-- Copyright   :  (c) Ross Paterson 2010
+-- License     :  BSD-style (see the file LICENSE)
+--
+-- Maintainer  :  R.Paterson@city.ac.uk
+-- Stability   :  experimental
+-- Portability :  portable
+--
+-- The constant functor.
+-----------------------------------------------------------------------------
+
+module Data.Functor.Constant (
+    Constant(..),
+  ) where
+
+import Data.Functor.Classes
+#if MIN_VERSION_base(4,12,0)
+import Data.Functor.Contravariant
+#endif
+
+import Control.Applicative
+import Data.Foldable
+import Data.Monoid (Monoid(..))
+import Data.Traversable (Traversable(traverse))
+#if MIN_VERSION_base(4,8,0)
+import Data.Bifunctor (Bifunctor(..))
+#endif
+#if MIN_VERSION_base(4,9,0)
+import Data.Semigroup (Semigroup(..))
+#endif
+#if MIN_VERSION_base(4,10,0)
+import Data.Bifoldable (Bifoldable(..))
+import Data.Bitraversable (Bitraversable(..))
+#endif
+import Prelude hiding (null, length)
+
+-- | Constant functor.
+newtype Constant a b = Constant { getConstant :: a }
+    deriving (Eq, Ord)
+
+-- These instances would be equivalent to the derived instances of the
+-- newtype if the field were removed.
+
+instance (Read a) => Read (Constant a b) where
+    readsPrec = readsData $
+         readsUnaryWith readsPrec "Constant" Constant
+
+instance (Show a) => Show (Constant a b) where
+    showsPrec d (Constant x) = showsUnaryWith showsPrec "Constant" d x
+
+-- Instances of lifted Prelude classes
+
+instance Eq2 Constant where
+    liftEq2 eq _ (Constant x) (Constant y) = eq x y
+    {-# INLINE liftEq2 #-}
+
+instance Ord2 Constant where
+    liftCompare2 comp _ (Constant x) (Constant y) = comp x y
+    {-# INLINE liftCompare2 #-}
+
+instance Read2 Constant where
+    liftReadsPrec2 rp _ _ _ = readsData $
+         readsUnaryWith rp "Constant" Constant
+
+instance Show2 Constant where
+    liftShowsPrec2 sp _ _ _ d (Constant x) = showsUnaryWith sp "Constant" d x
+
+instance (Eq a) => Eq1 (Constant a) where
+    liftEq = liftEq2 (==)
+    {-# INLINE liftEq #-}
+instance (Ord a) => Ord1 (Constant a) where
+    liftCompare = liftCompare2 compare
+    {-# INLINE liftCompare #-}
+instance (Read a) => Read1 (Constant a) where
+    liftReadsPrec = liftReadsPrec2 readsPrec readList
+    {-# INLINE liftReadsPrec #-}
+instance (Show a) => Show1 (Constant a) where
+    liftShowsPrec = liftShowsPrec2 showsPrec showList
+    {-# INLINE liftShowsPrec #-}
+
+instance Functor (Constant a) where
+    fmap _ (Constant x) = Constant x
+    {-# INLINE fmap #-}
+
+instance Foldable (Constant a) where
+    foldMap _ (Constant _) = mempty
+    {-# INLINE foldMap #-}
+#if MIN_VERSION_base(4,8,0)
+    null (Constant _) = True
+    length (Constant _) = 0
+#endif
+
+instance Traversable (Constant a) where
+    traverse _ (Constant x) = pure (Constant x)
+    {-# INLINE traverse #-}
+
+#if MIN_VERSION_base(4,9,0)
+instance (Semigroup a) => Semigroup (Constant a b) where
+    Constant x <> Constant y = Constant (x <> y)
+    {-# INLINE (<>) #-}
+#endif
+
+instance (Monoid a) => Applicative (Constant a) where
+    pure _ = Constant mempty
+    {-# INLINE pure #-}
+    Constant x <*> Constant y = Constant (x `mappend` y)
+    {-# INLINE (<*>) #-}
+
+instance (Monoid a) => Monoid (Constant a b) where
+    mempty = Constant mempty
+    {-# INLINE mempty #-}
+#if !MIN_VERSION_base(4,11,0)
+    -- From base-4.11, Monoid(mappend) defaults to Semigroup((<>))
+    Constant x `mappend` Constant y = Constant (x `mappend` y)
+    {-# INLINE mappend #-}
+#endif
+
+#if MIN_VERSION_base(4,8,0)
+instance Bifunctor Constant where
+    first f (Constant x) = Constant (f x)
+    {-# INLINE first #-}
+    second _ (Constant x) = Constant x
+    {-# INLINE second #-}
+#endif
+
+#if MIN_VERSION_base(4,10,0)
+instance Bifoldable Constant where
+    bifoldMap f _ (Constant a) = f a
+    {-# INLINE bifoldMap #-}
+
+instance Bitraversable Constant where
+    bitraverse f _ (Constant a) = Constant <$> f a
+    {-# INLINE bitraverse #-}
+#endif
+
+#if MIN_VERSION_base(4,12,0)
+instance Contravariant (Constant a) where
+    contramap _ (Constant a) = Constant a
+    {-# INLINE contramap #-}
+#endif

third_party/bazel/rules_haskell/examples/transformers/Data/Functor/Reverse.hs

@@ -0,0 +1,143 @@
+{-# LANGUAGE CPP #-}
+#if __GLASGOW_HASKELL__ >= 702
+{-# LANGUAGE Safe #-}
+#endif
+#if __GLASGOW_HASKELL__ >= 706
+{-# LANGUAGE PolyKinds #-}
+#endif
+#if __GLASGOW_HASKELL__ >= 710
+{-# LANGUAGE AutoDeriveTypeable #-}
+#endif
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Data.Functor.Reverse
+-- Copyright   :  (c) Russell O'Connor 2009
+-- License     :  BSD-style (see the file LICENSE)
+--
+-- Maintainer  :  R.Paterson@city.ac.uk
+-- Stability   :  experimental
+-- Portability :  portable
+--
+-- Making functors whose elements are notionally in the reverse order
+-- from the original functor.
+-----------------------------------------------------------------------------
+
+module Data.Functor.Reverse (
+    Reverse(..),
+  ) where
+
+import Control.Applicative.Backwards
+import Data.Functor.Classes
+#if MIN_VERSION_base(4,12,0)
+import Data.Functor.Contravariant
+#endif
+
+import Prelude hiding (foldr, foldr1, foldl, foldl1, null, length)
+import Control.Applicative
+import Control.Monad
+#if MIN_VERSION_base(4,9,0)
+import qualified Control.Monad.Fail as Fail
+#endif
+import Data.Foldable
+import Data.Traversable
+import Data.Monoid
+
+-- | The same functor, but with 'Foldable' and 'Traversable' instances
+-- that process the elements in the reverse order.
+newtype Reverse f a = Reverse { getReverse :: f a }
+
+instance (Eq1 f) => Eq1 (Reverse f) where
+    liftEq eq (Reverse x) (Reverse y) = liftEq eq x y
+    {-# INLINE liftEq #-}
+
+instance (Ord1 f) => Ord1 (Reverse f) where
+    liftCompare comp (Reverse x) (Reverse y) = liftCompare comp x y
+    {-# INLINE liftCompare #-}
+
+instance (Read1 f) => Read1 (Reverse f) where
+    liftReadsPrec rp rl = readsData $
+        readsUnaryWith (liftReadsPrec rp rl) "Reverse" Reverse
+
+instance (Show1 f) => Show1 (Reverse f) where
+    liftShowsPrec sp sl d (Reverse x) =
+        showsUnaryWith (liftShowsPrec sp sl) "Reverse" d x
+
+instance (Eq1 f, Eq a) => Eq (Reverse f a) where (==) = eq1
+instance (Ord1 f, Ord a) => Ord (Reverse f a) where compare = compare1
+instance (Read1 f, Read a) => Read (Reverse f a) where readsPrec = readsPrec1
+instance (Show1 f, Show a) => Show (Reverse f a) where showsPrec = showsPrec1
+
+-- | Derived instance.
+instance (Functor f) => Functor (Reverse f) where
+    fmap f (Reverse a) = Reverse (fmap f a)
+    {-# INLINE fmap #-}
+
+-- | Derived instance.
+instance (Applicative f) => Applicative (Reverse f) where
+    pure a = Reverse (pure a)
+    {-# INLINE pure #-}
+    Reverse f <*> Reverse a = Reverse (f <*> a)
+    {-# INLINE (<*>) #-}
+
+-- | Derived instance.
+instance (Alternative f) => Alternative (Reverse f) where
+    empty = Reverse empty
+    {-# INLINE empty #-}
+    Reverse x <|> Reverse y = Reverse (x <|> y)
+    {-# INLINE (<|>) #-}
+
+-- | Derived instance.
+instance (Monad m) => Monad (Reverse m) where
+#if !(MIN_VERSION_base(4,8,0))
+    return a = Reverse (return a)
+    {-# INLINE return #-}
+#endif
+    m >>= f = Reverse (getReverse m >>= getReverse . f)
+    {-# INLINE (>>=) #-}
+#if !(MIN_VERSION_base(4,13,0))
+    fail msg = Reverse (fail msg)
+    {-# INLINE fail #-}
+#endif
+
+#if MIN_VERSION_base(4,9,0)
+instance (Fail.MonadFail m) => Fail.MonadFail (Reverse m) where
+    fail msg = Reverse (Fail.fail msg)
+    {-# INLINE fail #-}
+#endif
+
+-- | Derived instance.
+instance (MonadPlus m) => MonadPlus (Reverse m) where
+    mzero = Reverse mzero
+    {-# INLINE mzero #-}
+    Reverse x `mplus` Reverse y = Reverse (x `mplus` y)
+    {-# INLINE mplus #-}
+
+-- | Fold from right to left.
+instance (Foldable f) => Foldable (Reverse f) where
+    foldMap f (Reverse t) = getDual (foldMap (Dual . f) t)
+    {-# INLINE foldMap #-}
+    foldr f z (Reverse t) = foldl (flip f) z t
+    {-# INLINE foldr #-}
+    foldl f z (Reverse t) = foldr (flip f) z t
+    {-# INLINE foldl #-}
+    foldr1 f (Reverse t) = foldl1 (flip f) t
+    {-# INLINE foldr1 #-}
+    foldl1 f (Reverse t) = foldr1 (flip f) t
+    {-# INLINE foldl1 #-}
+#if MIN_VERSION_base(4,8,0)
+    null (Reverse t) = null t
+    length (Reverse t) = length t
+#endif
+
+-- | Traverse from right to left.
+instance (Traversable f) => Traversable (Reverse f) where
+    traverse f (Reverse t) =
+        fmap Reverse . forwards $ traverse (Backwards . f) t
+    {-# INLINE traverse #-}
+
+#if MIN_VERSION_base(4,12,0)
+-- | Derived instance.
+instance Contravariant f => Contravariant (Reverse f) where
+    contramap f = Reverse . contramap f . getReverse
+    {-# INLINE contramap #-}
+#endif

third_party/bazel/rules_haskell/examples/transformers/LICENSE

@@ -0,0 +1,31 @@
+The Glasgow Haskell Compiler License
+
+Copyright 2004, The University Court of the University of Glasgow.
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+- Redistributions of source code must retain the above copyright notice,
+this list of conditions and the following disclaimer.
+
+- Redistributions in binary form must reproduce the above copyright notice,
+this list of conditions and the following disclaimer in the documentation
+and/or other materials provided with the distribution.
+
+- Neither name of the University nor the names of its contributors may be
+used to endorse or promote products derived from this software without
+specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY COURT OF THE UNIVERSITY OF
+GLASGOW AND THE CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
+INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+UNIVERSITY COURT OF THE UNIVERSITY OF GLASGOW OR THE CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
+DAMAGE.

third_party/bazel/rules_haskell/examples/transformers/Setup.hs

@@ -0,0 +1,2 @@
+import Distribution.Simple
+main = defaultMain

third_party/bazel/rules_haskell/examples/transformers/changelog

@@ -0,0 +1,124 @@
+-*-change-log-*-
+
+0.5.6.2 Ross Paterson <R.Paterson@city.ac.uk> Feb 2019
+	* Further backward compatability fix
+
+0.5.6.1 Ross Paterson <R.Paterson@city.ac.uk> Feb 2019
+	* Backward compatability fix for MonadFix ListT instance
+
+0.5.6.0 Ross Paterson <R.Paterson@city.ac.uk> Feb 2019
+	* Generalized type of except
+	* Added Control.Monad.Trans.Writer.CPS and Control.Monad.Trans.RWS.CPS
+	* Added Contravariant instances
+	* Added MonadFix instance for ListT
+
+0.5.5.0 Ross Paterson <R.Paterson@city.ac.uk> Oct 2017
+	* Added mapSelect and mapSelectT
+	* Renamed selectToCont to selectToContT for consistency
+	* Defined explicit method definitions to fix space leaks
+	* Added missing Semigroup instance to `Constant` functor
+
+0.5.4.0 Ross Paterson <R.Paterson@city.ac.uk> Feb 2017
+	* Migrate Bifoldable and Bitraversable instances for Constant
+
+0.5.3.1 Ross Paterson <R.Paterson@city.ac.uk> Feb 2017
+	* Fixed for pre-AMP environments
+
+0.5.3.0 Ross Paterson <R.Paterson@city.ac.uk> Feb 2017
+	* Added AccumT and SelectT monad transformers
+	* Deprecated ListT
+	* Added Monad (and related) instances for Reverse
+	* Added elimLift and eitherToErrors
+	* Added specialized definitions of several methods for efficiency
+	* Removed specialized definition of sequenceA for Reverse
+	* Backported Eq1/Ord1/Read1/Show1 instances for Proxy
+
+0.5.2.0 Ross Paterson <R.Paterson@city.ac.uk> Feb 2016
+	* Re-added orphan instances for Either to deprecated module
+	* Added lots of INLINE pragmas
+
+0.5.1.0 Ross Paterson <R.Paterson@city.ac.uk> Jan 2016
+	* Bump minor version number, required by added instances
+
+0.5.0.2 Ross Paterson <R.Paterson@city.ac.uk> Jan 2016
+	* Backported extra instances for Identity
+
+0.5.0.1 Ross Paterson <R.Paterson@city.ac.uk> Jan 2016
+	* Tightened GHC bounds for PolyKinds and DeriveDataTypeable
+
+0.5.0.0 Ross Paterson <R.Paterson@city.ac.uk> Dec 2015
+	* Control.Monad.IO.Class in base for GHC >= 8.0
+	* Data.Functor.{Classes,Compose,Product,Sum} in base for GHC >= 8.0
+	* Added PolyKinds for GHC >= 7.4
+	* Added instances of base classes MonadZip and MonadFail
+	* Changed liftings of Prelude classes to use explicit dictionaries
+
+0.4.3.0 Ross Paterson <R.Paterson@city.ac.uk> Mar 2015
+	* Added Eq1, Ord1, Show1 and Read1 instances for Const
+
+0.4.2.0 Ross Paterson <ross@soi.city.ac.uk> Nov 2014
+	* Dropped compatibility with base-1.x
+	* Data.Functor.Identity in base for GHC >= 7.10
+	* Added mapLift and runErrors to Control.Applicative.Lift
+	* Added AutoDeriveTypeable for GHC >= 7.10
+	* Expanded messages from mfix on ExceptT and MaybeT
+
+0.4.1.0 Ross Paterson <ross@soi.city.ac.uk> May 2014
+	* Reverted to record syntax for newtypes until next major release
+
+0.4.0.0 Ross Paterson <ross@soi.city.ac.uk> May 2014
+	* Added Sum type
+	* Added modify', a strict version of modify, to the state monads
+	* Added ExceptT and deprecated ErrorT
+	* Added infixr 9 `Compose` to match (.)
+	* Added Eq, Ord, Read and Show instances where possible
+	* Replaced record syntax for newtypes with separate inverse functions
+	* Added delimited continuation functions to ContT
+	* Added instance Alternative IO to ErrorT
+	* Handled disappearance of Control.Monad.Instances
+
+0.3.0.0 Ross Paterson <ross@soi.city.ac.uk> Mar 2012
+	* Added type synonyms for signatures of complex operations
+	* Generalized state, reader and writer constructor functions
+	* Added Lift, Backwards/Reverse
+	* Added MonadFix instances for IdentityT and MaybeT
+	* Added Foldable and Traversable instances
+	* Added Monad instances for Product
+
+0.2.2.1 Ross Paterson <ross@soi.city.ac.uk> Oct 2013
+	* Backport of fix for disappearance of Control.Monad.Instances
+
+0.2.2.0 Ross Paterson <ross@soi.city.ac.uk> Sep 2010
+	* Handled move of Either instances to base package
+
+0.2.1.0 Ross Paterson <ross@soi.city.ac.uk> Apr 2010
+	* Added Alternative instance for Compose
+	* Added Data.Functor.Product
+
+0.2.0.0 Ross Paterson <ross@soi.city.ac.uk> Mar 2010
+	* Added Constant and Compose
+	* Renamed modules to avoid clash with mtl
+	* Removed Monad constraint from Monad instance for ContT
+
+0.1.4.0 Ross Paterson <ross@soi.city.ac.uk> Mar 2009
+	* Adjusted lifting of Identity and Maybe transformers
+
+0.1.3.0 Ross Paterson <ross@soi.city.ac.uk> Mar 2009
+	* Added IdentityT transformer
+	* Added Applicative and Alternative instances for (Either e)
+
+0.1.1.0 Ross Paterson <ross@soi.city.ac.uk> Jan 2009
+	* Made all Functor instances assume Functor
+
+0.1.0.1 Ross Paterson <ross@soi.city.ac.uk> Jan 2009
+	* Adjusted dependencies
+
+0.1.0.0 Ross Paterson <ross@soi.city.ac.uk> Jan 2009
+	* Two versions of lifting of callcc through StateT
+	* Added Applicative instances
+
+0.0.1.0 Ross Paterson <ross@soi.city.ac.uk> Jan 2009
+	* Added constructors state, etc for simple monads
+
+0.0.0.0 Ross Paterson <ross@soi.city.ac.uk> Jan 2009
+	* Split Haskell 98 transformers from the mtl

third_party/bazel/rules_haskell/examples/transformers/legacy/pre709/Data/Functor/Identity.hs

@@ -0,0 +1,259 @@
+{-# LANGUAGE CPP #-}
+#if __GLASGOW_HASKELL__ >= 700
+{-# LANGUAGE DeriveDataTypeable #-}
+#endif
+#if __GLASGOW_HASKELL__ >= 702
+{-# LANGUAGE DeriveGeneric #-}
+{-# LANGUAGE Trustworthy #-}
+#endif
+#if __GLASGOW_HASKELL__ >= 706
+{-# LANGUAGE PolyKinds #-}
+#endif
+#if __GLASGOW_HASKELL__ >= 708
+{-# LANGUAGE AutoDeriveTypeable #-}
+{-# LANGUAGE DataKinds #-}
+#endif
+#if MIN_VERSION_base(4,7,0)
+-- We need to implement bitSize for the Bits instance, but it's deprecated.
+{-# OPTIONS_GHC -fno-warn-deprecations #-}
+#endif
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Data.Functor.Identity
+-- Copyright   :  (c) Andy Gill 2001,
+--                (c) Oregon Graduate Institute of Science and Technology 2001
+-- License     :  BSD-style (see the file LICENSE)
+--
+-- Maintainer  :  ross@soi.city.ac.uk
+-- Stability   :  experimental
+-- Portability :  portable
+--
+-- The identity functor and monad.
+--
+-- This trivial type constructor serves two purposes:
+--
+-- * It can be used with functions parameterized by functor or monad classes.
+--
+-- * It can be used as a base monad to which a series of monad
+--   transformers may be applied to construct a composite monad.
+--   Most monad transformer modules include the special case of
+--   applying the transformer to 'Identity'.  For example, @State s@
+--   is an abbreviation for @StateT s 'Identity'@.
+-----------------------------------------------------------------------------
+
+module Data.Functor.Identity (
+    Identity(..),
+  ) where
+
+import Data.Bits
+import Control.Applicative
+import Control.Arrow (Arrow((***)))
+import Control.Monad.Fix
+#if MIN_VERSION_base(4,4,0)
+import Control.Monad.Zip (MonadZip(mzipWith, munzip))
+#endif
+import Data.Foldable (Foldable(foldMap))
+import Data.Monoid (Monoid(mempty, mappend))
+import Data.String (IsString(fromString))
+import Data.Traversable (Traversable(traverse))
+#if __GLASGOW_HASKELL__ >= 700
+import Data.Data
+#endif
+import Data.Ix (Ix(..))
+import Foreign (Storable(..), castPtr)
+#if __GLASGOW_HASKELL__ >= 702
+import GHC.Generics
+#endif
+
+-- | Identity functor and monad. (a non-strict monad)
+newtype Identity a = Identity { runIdentity :: a }
+    deriving ( Eq, Ord
+#if __GLASGOW_HASKELL__ >= 700
+             , Data, Typeable
+#endif
+#if __GLASGOW_HASKELL__ >= 702
+             , Generic
+#endif
+#if __GLASGOW_HASKELL__ >= 706
+             , Generic1
+#endif
+             )
+
+instance (Bits a) => Bits (Identity a) where
+    Identity x .&. Identity y     = Identity (x .&. y)
+    Identity x .|. Identity y     = Identity (x .|. y)
+    xor (Identity x) (Identity y) = Identity (xor x y)
+    complement   (Identity x)     = Identity (complement x)
+    shift        (Identity x) i   = Identity (shift    x i)
+    rotate       (Identity x) i   = Identity (rotate   x i)
+    setBit       (Identity x) i   = Identity (setBit   x i)
+    clearBit     (Identity x) i   = Identity (clearBit x i)
+    shiftL       (Identity x) i   = Identity (shiftL   x i)
+    shiftR       (Identity x) i   = Identity (shiftR   x i)
+    rotateL      (Identity x) i   = Identity (rotateL  x i)
+    rotateR      (Identity x) i   = Identity (rotateR  x i)
+    testBit      (Identity x) i   = testBit x i
+    bitSize      (Identity x)     = bitSize x
+    isSigned     (Identity x)     = isSigned x
+    bit i                         = Identity (bit i)
+#if MIN_VERSION_base(4,5,0)
+    unsafeShiftL (Identity x) i   = Identity (unsafeShiftL x i)
+    unsafeShiftR (Identity x) i   = Identity (unsafeShiftR x i)
+    popCount     (Identity x)     = popCount x
+#endif
+#if MIN_VERSION_base(4,7,0)
+    zeroBits                      = Identity zeroBits
+    bitSizeMaybe (Identity x)     = bitSizeMaybe x
+#endif
+
+instance (Bounded a) => Bounded (Identity a) where
+    minBound = Identity minBound
+    maxBound = Identity maxBound
+
+instance (Enum a) => Enum (Identity a) where
+    succ (Identity x)     = Identity (succ x)
+    pred (Identity x)     = Identity (pred x)
+    toEnum i              = Identity (toEnum i)
+    fromEnum (Identity x) = fromEnum x
+    enumFrom (Identity x) = map Identity (enumFrom x)
+    enumFromThen (Identity x) (Identity y) = map Identity (enumFromThen x y)
+    enumFromTo   (Identity x) (Identity y) = map Identity (enumFromTo   x y)
+    enumFromThenTo (Identity x) (Identity y) (Identity z) =
+        map Identity (enumFromThenTo x y z)
+
+#if MIN_VERSION_base(4,7,0)
+instance (FiniteBits a) => FiniteBits (Identity a) where
+    finiteBitSize (Identity x) = finiteBitSize x
+#endif
+
+instance (Floating a) => Floating (Identity a) where
+    pi                                = Identity pi
+    exp   (Identity x)                = Identity (exp x)
+    log   (Identity x)                = Identity (log x)
+    sqrt  (Identity x)                = Identity (sqrt x)
+    sin   (Identity x)                = Identity (sin x)
+    cos   (Identity x)                = Identity (cos x)
+    tan   (Identity x)                = Identity (tan x)
+    asin  (Identity x)                = Identity (asin x)
+    acos  (Identity x)                = Identity (acos x)
+    atan  (Identity x)                = Identity (atan x)
+    sinh  (Identity x)                = Identity (sinh x)
+    cosh  (Identity x)                = Identity (cosh x)
+    tanh  (Identity x)                = Identity (tanh x)
+    asinh (Identity x)                = Identity (asinh x)
+    acosh (Identity x)                = Identity (acosh x)
+    atanh (Identity x)                = Identity (atanh x)
+    Identity x ** Identity y          = Identity (x ** y)
+    logBase (Identity x) (Identity y) = Identity (logBase x y)
+
+instance (Fractional a) => Fractional (Identity a) where
+    Identity x / Identity y = Identity (x / y)
+    recip (Identity x)      = Identity (recip x)
+    fromRational r          = Identity (fromRational r)
+
+instance (IsString a) => IsString (Identity a) where
+    fromString s = Identity (fromString s)
+
+instance (Ix a) => Ix (Identity a) where
+    range     (Identity x, Identity y) = map Identity (range (x, y))
+    index     (Identity x, Identity y) (Identity i) = index     (x, y) i
+    inRange   (Identity x, Identity y) (Identity e) = inRange   (x, y) e
+    rangeSize (Identity x, Identity y) = rangeSize (x, y)
+
+instance (Integral a) => Integral (Identity a) where
+    quot    (Identity x) (Identity y) = Identity (quot x y)
+    rem     (Identity x) (Identity y) = Identity (rem  x y)
+    div     (Identity x) (Identity y) = Identity (div  x y)
+    mod     (Identity x) (Identity y) = Identity (mod  x y)
+    quotRem (Identity x) (Identity y) = (Identity *** Identity) (quotRem x y)
+    divMod  (Identity x) (Identity y) = (Identity *** Identity) (divMod  x y)
+    toInteger (Identity x)            = toInteger x
+
+instance (Monoid a) => Monoid (Identity a) where
+    mempty = Identity mempty
+    mappend (Identity x) (Identity y) = Identity (mappend x y)
+
+instance (Num a) => Num (Identity a) where
+    Identity x + Identity y = Identity (x + y)
+    Identity x - Identity y = Identity (x - y)
+    Identity x * Identity y = Identity (x * y)
+    negate (Identity x)     = Identity (negate x)
+    abs    (Identity x)     = Identity (abs    x)
+    signum (Identity x)     = Identity (signum x)
+    fromInteger n           = Identity (fromInteger n)
+
+instance (Real a) => Real (Identity a) where
+    toRational (Identity x) = toRational x
+
+instance (RealFloat a) => RealFloat (Identity a) where
+    floatRadix     (Identity x)     = floatRadix     x
+    floatDigits    (Identity x)     = floatDigits    x
+    floatRange     (Identity x)     = floatRange     x
+    decodeFloat    (Identity x)     = decodeFloat    x
+    exponent       (Identity x)     = exponent       x
+    isNaN          (Identity x)     = isNaN          x
+    isInfinite     (Identity x)     = isInfinite     x
+    isDenormalized (Identity x)     = isDenormalized x
+    isNegativeZero (Identity x)     = isNegativeZero x
+    isIEEE         (Identity x)     = isIEEE         x
+    significand    (Identity x)     = significand (Identity x)
+    scaleFloat s   (Identity x)     = Identity (scaleFloat s x)
+    encodeFloat m n                 = Identity (encodeFloat m n)
+    atan2 (Identity x) (Identity y) = Identity (atan2 x y)
+
+instance (RealFrac a) => RealFrac (Identity a) where
+    properFraction (Identity x) = (id *** Identity) (properFraction x)
+    truncate       (Identity x) = truncate x
+    round          (Identity x) = round    x
+    ceiling        (Identity x) = ceiling  x
+    floor          (Identity x) = floor    x
+
+instance (Storable a) => Storable (Identity a) where
+    sizeOf    (Identity x)       = sizeOf x
+    alignment (Identity x)       = alignment x
+    peekElemOff p i              = fmap Identity (peekElemOff (castPtr p) i)
+    pokeElemOff p i (Identity x) = pokeElemOff (castPtr p) i x
+    peekByteOff p i              = fmap Identity (peekByteOff p i)
+    pokeByteOff p i (Identity x) = pokeByteOff p i x
+    peek p                       = fmap runIdentity (peek (castPtr p))
+    poke p (Identity x)          = poke (castPtr p) x
+
+-- These instances would be equivalent to the derived instances of the
+-- newtype if the field were removed.
+
+instance (Read a) => Read (Identity a) where
+    readsPrec d = readParen (d > 10) $ \ r ->
+        [(Identity x,t) | ("Identity",s) <- lex r, (x,t) <- readsPrec 11 s]
+
+instance (Show a) => Show (Identity a) where
+    showsPrec d (Identity x) = showParen (d > 10) $
+        showString "Identity " . showsPrec 11 x
+
+-- ---------------------------------------------------------------------------
+-- Identity instances for Functor and Monad
+
+instance Functor Identity where
+    fmap f m = Identity (f (runIdentity m))
+
+instance Foldable Identity where
+    foldMap f (Identity x) = f x
+
+instance Traversable Identity where
+    traverse f (Identity x) = Identity <$> f x
+
+instance Applicative Identity where
+    pure a = Identity a
+    Identity f <*> Identity x = Identity (f x)
+
+instance Monad Identity where
+    return a = Identity a
+    m >>= k  = k (runIdentity m)
+
+instance MonadFix Identity where
+    mfix f = Identity (fix (runIdentity . f))
+
+#if MIN_VERSION_base(4,4,0)
+instance MonadZip Identity where
+    mzipWith f (Identity x) (Identity y) = Identity (f x y)
+    munzip (Identity (a, b)) = (Identity a, Identity b)
+#endif

third_party/bazel/rules_haskell/examples/transformers/legacy/pre711/Control/Monad/IO/Class.hs

@@ -0,0 +1,51 @@
+{-# LANGUAGE CPP #-}
+#if __GLASGOW_HASKELL__ >= 702
+{-# LANGUAGE Safe #-}
+#endif
+#if __GLASGOW_HASKELL__ >= 708
+{-# LANGUAGE DeriveDataTypeable #-}
+{-# LANGUAGE StandaloneDeriving #-}
+#endif
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Control.Monad.IO.Class
+-- Copyright   :  (c) Andy Gill 2001,
+--                (c) Oregon Graduate Institute of Science and Technology, 2001
+-- License     :  BSD-style (see the file LICENSE)
+--
+-- Maintainer  :  R.Paterson@city.ac.uk
+-- Stability   :  experimental
+-- Portability :  portable
+--
+-- Class of monads based on @IO@.
+-----------------------------------------------------------------------------
+
+module Control.Monad.IO.Class (
+    MonadIO(..)
+  ) where
+
+#if __GLASGOW_HASKELL__ >= 708
+import Data.Typeable
+#endif
+
+-- | Monads in which 'IO' computations may be embedded.
+-- Any monad built by applying a sequence of monad transformers to the
+-- 'IO' monad will be an instance of this class.
+--
+-- Instances should satisfy the following laws, which state that 'liftIO'
+-- is a transformer of monads:
+--
+-- * @'liftIO' . 'return' = 'return'@
+--
+-- * @'liftIO' (m >>= f) = 'liftIO' m >>= ('liftIO' . f)@
+
+class (Monad m) => MonadIO m where
+    -- | Lift a computation from the 'IO' monad.
+    liftIO :: IO a -> m a
+
+#if __GLASGOW_HASKELL__ >= 708
+deriving instance Typeable MonadIO
+#endif
+
+instance MonadIO IO where
+    liftIO = id

third_party/bazel/rules_haskell/examples/transformers/legacy/pre711/Data/Functor/Classes.hs

@@ -0,0 +1,529 @@
+{-# LANGUAGE CPP #-}
+#if __GLASGOW_HASKELL__ >= 702
+{-# LANGUAGE Safe #-}
+#endif
+#if __GLASGOW_HASKELL__ >= 708
+{-# LANGUAGE DeriveDataTypeable #-}
+{-# LANGUAGE StandaloneDeriving #-}
+#endif
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Data.Functor.Classes
+-- Copyright   :  (c) Ross Paterson 2013
+-- License     :  BSD-style (see the file LICENSE)
+--
+-- Maintainer  :  R.Paterson@city.ac.uk
+-- Stability   :  experimental
+-- Portability :  portable
+--
+-- Liftings of the Prelude classes 'Eq', 'Ord', 'Read' and 'Show' to
+-- unary and binary type constructors.
+--
+-- These classes are needed to express the constraints on arguments of
+-- transformers in portable Haskell.  Thus for a new transformer @T@,
+-- one might write instances like
+--
+-- > instance (Eq1 f) => Eq1 (T f) where ...
+-- > instance (Ord1 f) => Ord1 (T f) where ...
+-- > instance (Read1 f) => Read1 (T f) where ...
+-- > instance (Show1 f) => Show1 (T f) where ...
+--
+-- If these instances can be defined, defining instances of the base
+-- classes is mechanical:
+--
+-- > instance (Eq1 f, Eq a) => Eq (T f a) where (==) = eq1
+-- > instance (Ord1 f, Ord a) => Ord (T f a) where compare = compare1
+-- > instance (Read1 f, Read a) => Read (T f a) where readsPrec = readsPrec1
+-- > instance (Show1 f, Show a) => Show (T f a) where showsPrec = showsPrec1
+--
+-----------------------------------------------------------------------------
+
+module Data.Functor.Classes (
+    -- * Liftings of Prelude classes
+    -- ** For unary constructors
+    Eq1(..), eq1,
+    Ord1(..), compare1,
+    Read1(..), readsPrec1,
+    Show1(..), showsPrec1,
+    -- ** For binary constructors
+    Eq2(..), eq2,
+    Ord2(..), compare2,
+    Read2(..), readsPrec2,
+    Show2(..), showsPrec2,
+    -- * Helper functions
+    -- $example
+    readsData,
+    readsUnaryWith,
+    readsBinaryWith,
+    showsUnaryWith,
+    showsBinaryWith,
+    -- ** Obsolete helpers
+    readsUnary,
+    readsUnary1,
+    readsBinary1,
+    showsUnary,
+    showsUnary1,
+    showsBinary1,
+  ) where
+
+import Control.Applicative (Const(Const))
+import Data.Functor.Identity (Identity(Identity))
+import Data.Monoid (mappend)
+#if MIN_VERSION_base(4,7,0)
+import Data.Proxy (Proxy(Proxy))
+#endif
+#if __GLASGOW_HASKELL__ >= 708
+import Data.Typeable
+#endif
+import Text.Show (showListWith)
+
+-- | Lifting of the 'Eq' class to unary type constructors.
+class Eq1 f where
+    -- | Lift an equality test through the type constructor.
+    --
+    -- The function will usually be applied to an equality function,
+    -- but the more general type ensures that the implementation uses
+    -- it to compare elements of the first container with elements of
+    -- the second.
+    liftEq :: (a -> b -> Bool) -> f a -> f b -> Bool
+
+#if __GLASGOW_HASKELL__ >= 708
+deriving instance Typeable Eq1
+#endif
+
+-- | Lift the standard @('==')@ function through the type constructor.
+eq1 :: (Eq1 f, Eq a) => f a -> f a -> Bool
+eq1 = liftEq (==)
+
+-- | Lifting of the 'Ord' class to unary type constructors.
+class (Eq1 f) => Ord1 f where
+    -- | Lift a 'compare' function through the type constructor.
+    --
+    -- The function will usually be applied to a comparison function,
+    -- but the more general type ensures that the implementation uses
+    -- it to compare elements of the first container with elements of
+    -- the second.
+    liftCompare :: (a -> b -> Ordering) -> f a -> f b -> Ordering
+
+#if __GLASGOW_HASKELL__ >= 708
+deriving instance Typeable Ord1
+#endif
+
+-- | Lift the standard 'compare' function through the type constructor.
+compare1 :: (Ord1 f, Ord a) => f a -> f a -> Ordering
+compare1 = liftCompare compare
+
+-- | Lifting of the 'Read' class to unary type constructors.
+class Read1 f where
+    -- | 'readsPrec' function for an application of the type constructor
+    -- based on 'readsPrec' and 'readList' functions for the argument type.
+    liftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (f a)
+
+    -- | 'readList' function for an application of the type constructor
+    -- based on 'readsPrec' and 'readList' functions for the argument type.
+    -- The default implementation using standard list syntax is correct
+    -- for most types.
+    liftReadList :: (Int -> ReadS a) -> ReadS [a] -> ReadS [f a]
+    liftReadList rp rl = readListWith (liftReadsPrec rp rl 0)
+
+#if __GLASGOW_HASKELL__ >= 708
+deriving instance Typeable Read1
+#endif
+
+-- | Read a list (using square brackets and commas), given a function
+-- for reading elements.
+readListWith :: ReadS a -> ReadS [a]
+readListWith rp =
+    readParen False (\r -> [pr | ("[",s) <- lex r, pr <- readl s])
+  where
+    readl s = [([],t) | ("]",t) <- lex s] ++
+        [(x:xs,u) | (x,t) <- rp s, (xs,u) <- readl' t]
+    readl' s = [([],t) | ("]",t) <- lex s] ++
+        [(x:xs,v) | (",",t) <- lex s, (x,u) <- rp t, (xs,v) <- readl' u]
+
+-- | Lift the standard 'readsPrec' and 'readList' functions through the
+-- type constructor.
+readsPrec1 :: (Read1 f, Read a) => Int -> ReadS (f a)
+readsPrec1 = liftReadsPrec readsPrec readList
+
+-- | Lifting of the 'Show' class to unary type constructors.
+class Show1 f where
+    -- | 'showsPrec' function for an application of the type constructor
+    -- based on 'showsPrec' and 'showList' functions for the argument type.
+    liftShowsPrec :: (Int -> a -> ShowS) -> ([a] -> ShowS) ->
+        Int -> f a -> ShowS
+
+    -- | 'showList' function for an application of the type constructor
+    -- based on 'showsPrec' and 'showList' functions for the argument type.
+    -- The default implementation using standard list syntax is correct
+    -- for most types.
+    liftShowList :: (Int -> a -> ShowS) -> ([a] -> ShowS) ->
+        [f a] -> ShowS
+    liftShowList sp sl = showListWith (liftShowsPrec sp sl 0)
+
+#if __GLASGOW_HASKELL__ >= 708
+deriving instance Typeable Show1
+#endif
+
+-- | Lift the standard 'showsPrec' and 'showList' functions through the
+-- type constructor.
+showsPrec1 :: (Show1 f, Show a) => Int -> f a -> ShowS
+showsPrec1 = liftShowsPrec showsPrec showList
+
+-- | Lifting of the 'Eq' class to binary type constructors.
+class Eq2 f where
+    -- | Lift equality tests through the type constructor.
+    --
+    -- The function will usually be applied to equality functions,
+    -- but the more general type ensures that the implementation uses
+    -- them to compare elements of the first container with elements of
+    -- the second.
+    liftEq2 :: (a -> b -> Bool) -> (c -> d -> Bool) -> f a c -> f b d -> Bool
+
+#if __GLASGOW_HASKELL__ >= 708
+deriving instance Typeable Eq2
+#endif
+
+-- | Lift the standard @('==')@ function through the type constructor.
+eq2 :: (Eq2 f, Eq a, Eq b) => f a b -> f a b -> Bool
+eq2 = liftEq2 (==) (==)
+
+-- | Lifting of the 'Ord' class to binary type constructors.
+class (Eq2 f) => Ord2 f where
+    -- | Lift 'compare' functions through the type constructor.
+    --
+    -- The function will usually be applied to comparison functions,
+    -- but the more general type ensures that the implementation uses
+    -- them to compare elements of the first container with elements of
+    -- the second.
+    liftCompare2 :: (a -> b -> Ordering) -> (c -> d -> Ordering) ->
+        f a c -> f b d -> Ordering
+
+#if __GLASGOW_HASKELL__ >= 708
+deriving instance Typeable Ord2
+#endif
+
+-- | Lift the standard 'compare' function through the type constructor.
+compare2 :: (Ord2 f, Ord a, Ord b) => f a b -> f a b -> Ordering
+compare2 = liftCompare2 compare compare
+
+-- | Lifting of the 'Read' class to binary type constructors.
+class Read2 f where
+    -- | 'readsPrec' function for an application of the type constructor
+    -- based on 'readsPrec' and 'readList' functions for the argument types.
+    liftReadsPrec2 :: (Int -> ReadS a) -> ReadS [a] ->
+        (Int -> ReadS b) -> ReadS [b] -> Int -> ReadS (f a b)
+
+    -- | 'readList' function for an application of the type constructor
+    -- based on 'readsPrec' and 'readList' functions for the argument types.
+    -- The default implementation using standard list syntax is correct
+    -- for most types.
+    liftReadList2 :: (Int -> ReadS a) -> ReadS [a] ->
+        (Int -> ReadS b) -> ReadS [b] -> ReadS [f a b]
+    liftReadList2 rp1 rl1 rp2 rl2 =
+        readListWith (liftReadsPrec2 rp1 rl1 rp2 rl2 0)
+
+#if __GLASGOW_HASKELL__ >= 708
+deriving instance Typeable Read2
+#endif
+
+-- | Lift the standard 'readsPrec' function through the type constructor.
+readsPrec2 :: (Read2 f, Read a, Read b) => Int -> ReadS (f a b)
+readsPrec2 = liftReadsPrec2 readsPrec readList readsPrec readList
+
+-- | Lifting of the 'Show' class to binary type constructors.
+class Show2 f where
+    -- | 'showsPrec' function for an application of the type constructor
+    -- based on 'showsPrec' and 'showList' functions for the argument types.
+    liftShowsPrec2 :: (Int -> a -> ShowS) -> ([a] -> ShowS) ->
+        (Int -> b -> ShowS) -> ([b] -> ShowS) -> Int -> f a b -> ShowS
+
+    -- | 'showList' function for an application of the type constructor
+    -- based on 'showsPrec' and 'showList' functions for the argument types.
+    -- The default implementation using standard list syntax is correct
+    -- for most types.
+    liftShowList2 :: (Int -> a -> ShowS) -> ([a] -> ShowS) ->
+        (Int -> b -> ShowS) -> ([b] -> ShowS) -> [f a b] -> ShowS
+    liftShowList2 sp1 sl1 sp2 sl2 =
+        showListWith (liftShowsPrec2 sp1 sl1 sp2 sl2 0)
+
+#if __GLASGOW_HASKELL__ >= 708
+deriving instance Typeable Show2
+#endif
+
+-- | Lift the standard 'showsPrec' function through the type constructor.
+showsPrec2 :: (Show2 f, Show a, Show b) => Int -> f a b -> ShowS
+showsPrec2 = liftShowsPrec2 showsPrec showList showsPrec showList
+
+-- Instances for Prelude type constructors
+
+instance Eq1 Maybe where
+    liftEq _ Nothing Nothing = True
+    liftEq _ Nothing (Just _) = False
+    liftEq _ (Just _) Nothing = False
+    liftEq eq (Just x) (Just y) = eq x y
+
+instance Ord1 Maybe where
+    liftCompare _ Nothing Nothing = EQ
+    liftCompare _ Nothing (Just _) = LT
+    liftCompare _ (Just _) Nothing = GT
+    liftCompare comp (Just x) (Just y) = comp x y
+
+instance Read1 Maybe where
+    liftReadsPrec rp _ d =
+         readParen False (\ r -> [(Nothing,s) | ("Nothing",s) <- lex r])
+         `mappend`
+         readsData (readsUnaryWith rp "Just" Just) d
+
+instance Show1 Maybe where
+    liftShowsPrec _ _ _ Nothing = showString "Nothing"
+    liftShowsPrec sp _ d (Just x) = showsUnaryWith sp "Just" d x
+
+instance Eq1 [] where
+    liftEq _ [] [] = True
+    liftEq _ [] (_:_) = False
+    liftEq _ (_:_) [] = False
+    liftEq eq (x:xs) (y:ys) = eq x y && liftEq eq xs ys
+
+instance Ord1 [] where
+    liftCompare _ [] [] = EQ
+    liftCompare _ [] (_:_) = LT
+    liftCompare _ (_:_) [] = GT
+    liftCompare comp (x:xs) (y:ys) = comp x y `mappend` liftCompare comp xs ys
+
+instance Read1 [] where
+    liftReadsPrec _ rl _ = rl
+
+instance Show1 [] where
+    liftShowsPrec _ sl _ = sl
+
+instance Eq2 (,) where
+    liftEq2 e1 e2 (x1, y1) (x2, y2) = e1 x1 x2 && e2 y1 y2
+
+instance Ord2 (,) where
+    liftCompare2 comp1 comp2 (x1, y1) (x2, y2) =
+        comp1 x1 x2 `mappend` comp2 y1 y2
+
+instance Read2 (,) where
+    liftReadsPrec2 rp1 _ rp2 _ _ = readParen False $ \ r ->
+        [((x,y), w) | ("(",s) <- lex r,
+                      (x,t)   <- rp1 0 s,
+                      (",",u) <- lex t,
+                      (y,v)   <- rp2 0 u,
+                      (")",w) <- lex v]
+
+instance Show2 (,) where
+    liftShowsPrec2 sp1 _ sp2 _ _ (x, y) =
+        showChar '(' . sp1 0 x . showChar ',' . sp2 0 y . showChar ')'
+
+instance (Eq a) => Eq1 ((,) a) where
+    liftEq = liftEq2 (==)
+
+instance (Ord a) => Ord1 ((,) a) where
+    liftCompare = liftCompare2 compare
+
+instance (Read a) => Read1 ((,) a) where
+    liftReadsPrec = liftReadsPrec2 readsPrec readList
+
+instance (Show a) => Show1 ((,) a) where
+    liftShowsPrec = liftShowsPrec2 showsPrec showList
+
+instance Eq2 Either where
+    liftEq2 e1 _ (Left x) (Left y) = e1 x y
+    liftEq2 _ _ (Left _) (Right _) = False
+    liftEq2 _ _ (Right _) (Left _) = False
+    liftEq2 _ e2 (Right x) (Right y) = e2 x y
+
+instance Ord2 Either where
+    liftCompare2 comp1 _ (Left x) (Left y) = comp1 x y
+    liftCompare2 _ _ (Left _) (Right _) = LT
+    liftCompare2 _ _ (Right _) (Left _) = GT
+    liftCompare2 _ comp2 (Right x) (Right y) = comp2 x y
+
+instance Read2 Either where
+    liftReadsPrec2 rp1 _ rp2 _ = readsData $
+         readsUnaryWith rp1 "Left" Left `mappend`
+         readsUnaryWith rp2 "Right" Right
+
+instance Show2 Either where
+    liftShowsPrec2 sp1 _ _ _ d (Left x) = showsUnaryWith sp1 "Left" d x
+    liftShowsPrec2 _ _ sp2 _ d (Right x) = showsUnaryWith sp2 "Right" d x
+
+instance (Eq a) => Eq1 (Either a) where
+    liftEq = liftEq2 (==)
+
+instance (Ord a) => Ord1 (Either a) where
+    liftCompare = liftCompare2 compare
+
+instance (Read a) => Read1 (Either a) where
+    liftReadsPrec = liftReadsPrec2 readsPrec readList
+
+instance (Show a) => Show1 (Either a) where
+    liftShowsPrec = liftShowsPrec2 showsPrec showList
+
+#if MIN_VERSION_base(4,7,0)
+instance Eq1 Proxy where
+    liftEq _ _ _ = True
+
+instance Ord1 Proxy where
+    liftCompare _ _ _ = EQ
+
+instance Show1 Proxy where
+    liftShowsPrec _ _ _ _ = showString "Proxy"
+
+instance Read1 Proxy where
+    liftReadsPrec _ _ d =
+        readParen (d > 10) (\r -> [(Proxy, s) | ("Proxy",s) <- lex r ])
+#endif
+
+-- Instances for other functors defined in the base package
+
+instance Eq1 Identity where
+    liftEq eq (Identity x) (Identity y) = eq x y
+
+instance Ord1 Identity where
+    liftCompare comp (Identity x) (Identity y) = comp x y
+
+instance Read1 Identity where
+    liftReadsPrec rp _ = readsData $
+         readsUnaryWith rp "Identity" Identity
+
+instance Show1 Identity where
+    liftShowsPrec sp _ d (Identity x) = showsUnaryWith sp "Identity" d x
+
+instance Eq2 Const where
+    liftEq2 eq _ (Const x) (Const y) = eq x y
+
+instance Ord2 Const where
+    liftCompare2 comp _ (Const x) (Const y) = comp x y
+
+instance Read2 Const where
+    liftReadsPrec2 rp _ _ _ = readsData $
+         readsUnaryWith rp "Const" Const
+
+instance Show2 Const where
+    liftShowsPrec2 sp _ _ _ d (Const x) = showsUnaryWith sp "Const" d x
+
+instance (Eq a) => Eq1 (Const a) where
+    liftEq = liftEq2 (==)
+instance (Ord a) => Ord1 (Const a) where
+    liftCompare = liftCompare2 compare
+instance (Read a) => Read1 (Const a) where
+    liftReadsPrec = liftReadsPrec2 readsPrec readList
+instance (Show a) => Show1 (Const a) where
+    liftShowsPrec = liftShowsPrec2 showsPrec showList
+
+-- Building blocks
+
+-- | @'readsData' p d@ is a parser for datatypes where each alternative
+-- begins with a data constructor.  It parses the constructor and
+-- passes it to @p@.  Parsers for various constructors can be constructed
+-- with 'readsUnary', 'readsUnary1' and 'readsBinary1', and combined with
+-- @mappend@ from the @Monoid@ class.
+readsData :: (String -> ReadS a) -> Int -> ReadS a
+readsData reader d =
+    readParen (d > 10) $ \ r -> [res | (kw,s) <- lex r, res <- reader kw s]
+
+-- | @'readsUnaryWith' rp n c n'@ matches the name of a unary data constructor
+-- and then parses its argument using @rp@.
+readsUnaryWith :: (Int -> ReadS a) -> String -> (a -> t) -> String -> ReadS t
+readsUnaryWith rp name cons kw s =
+    [(cons x,t) | kw == name, (x,t) <- rp 11 s]
+
+-- | @'readsBinaryWith' rp1 rp2 n c n'@ matches the name of a binary
+-- data constructor and then parses its arguments using @rp1@ and @rp2@
+-- respectively.
+readsBinaryWith :: (Int -> ReadS a) -> (Int -> ReadS b) ->
+    String -> (a -> b -> t) -> String -> ReadS t
+readsBinaryWith rp1 rp2 name cons kw s =
+    [(cons x y,u) | kw == name, (x,t) <- rp1 11 s, (y,u) <- rp2 11 t]
+
+-- | @'showsUnaryWith' sp n d x@ produces the string representation of a
+-- unary data constructor with name @n@ and argument @x@, in precedence
+-- context @d@.
+showsUnaryWith :: (Int -> a -> ShowS) -> String -> Int -> a -> ShowS
+showsUnaryWith sp name d x = showParen (d > 10) $
+    showString name . showChar ' ' . sp 11 x
+
+-- | @'showsBinaryWith' sp1 sp2 n d x y@ produces the string
+-- representation of a binary data constructor with name @n@ and arguments
+-- @x@ and @y@, in precedence context @d@.
+showsBinaryWith :: (Int -> a -> ShowS) -> (Int -> b -> ShowS) ->
+    String -> Int -> a -> b -> ShowS
+showsBinaryWith sp1 sp2 name d x y = showParen (d > 10) $
+    showString name . showChar ' ' . sp1 11 x . showChar ' ' . sp2 11 y
+
+-- Obsolete building blocks
+
+-- | @'readsUnary' n c n'@ matches the name of a unary data constructor
+-- and then parses its argument using 'readsPrec'.
+{-# DEPRECATED readsUnary "Use readsUnaryWith to define liftReadsPrec" #-}
+readsUnary :: (Read a) => String -> (a -> t) -> String -> ReadS t
+readsUnary name cons kw s =
+    [(cons x,t) | kw == name, (x,t) <- readsPrec 11 s]
+
+-- | @'readsUnary1' n c n'@ matches the name of a unary data constructor
+-- and then parses its argument using 'readsPrec1'.
+{-# DEPRECATED readsUnary1 "Use readsUnaryWith to define liftReadsPrec" #-}
+readsUnary1 :: (Read1 f, Read a) => String -> (f a -> t) -> String -> ReadS t
+readsUnary1 name cons kw s =
+    [(cons x,t) | kw == name, (x,t) <- readsPrec1 11 s]
+
+-- | @'readsBinary1' n c n'@ matches the name of a binary data constructor
+-- and then parses its arguments using 'readsPrec1'.
+{-# DEPRECATED readsBinary1 "Use readsBinaryWith to define liftReadsPrec" #-}
+readsBinary1 :: (Read1 f, Read1 g, Read a) =>
+    String -> (f a -> g a -> t) -> String -> ReadS t
+readsBinary1 name cons kw s =
+    [(cons x y,u) | kw == name,
+        (x,t) <- readsPrec1 11 s, (y,u) <- readsPrec1 11 t]
+
+-- | @'showsUnary' n d x@ produces the string representation of a unary data
+-- constructor with name @n@ and argument @x@, in precedence context @d@.
+{-# DEPRECATED showsUnary "Use showsUnaryWith to define liftShowsPrec" #-}
+showsUnary :: (Show a) => String -> Int -> a -> ShowS
+showsUnary name d x = showParen (d > 10) $
+    showString name . showChar ' ' . showsPrec 11 x
+
+-- | @'showsUnary1' n d x@ produces the string representation of a unary data
+-- constructor with name @n@ and argument @x@, in precedence context @d@.
+{-# DEPRECATED showsUnary1 "Use showsUnaryWith to define liftShowsPrec" #-}
+showsUnary1 :: (Show1 f, Show a) => String -> Int -> f a -> ShowS
+showsUnary1 name d x = showParen (d > 10) $
+    showString name . showChar ' ' . showsPrec1 11 x
+
+-- | @'showsBinary1' n d x y@ produces the string representation of a binary
+-- data constructor with name @n@ and arguments @x@ and @y@, in precedence
+-- context @d@.
+{-# DEPRECATED showsBinary1 "Use showsBinaryWith to define liftShowsPrec" #-}
+showsBinary1 :: (Show1 f, Show1 g, Show a) =>
+    String -> Int -> f a -> g a -> ShowS
+showsBinary1 name d x y = showParen (d > 10) $
+    showString name . showChar ' ' . showsPrec1 11 x .
+        showChar ' ' . showsPrec1 11 y
+
+{- $example
+These functions can be used to assemble 'Read' and 'Show' instances for
+new algebraic types.  For example, given the definition
+
+> data T f a = Zero a | One (f a) | Two a (f a)
+
+a standard 'Read1' instance may be defined as
+
+> instance (Read1 f) => Read1 (T f) where
+>     liftReadsPrec rp rl = readsData $
+>         readsUnaryWith rp "Zero" Zero `mappend`
+>         readsUnaryWith (liftReadsPrec rp rl) "One" One `mappend`
+>         readsBinaryWith rp (liftReadsPrec rp rl) "Two" Two
+
+and the corresponding 'Show1' instance as
+
+> instance (Show1 f) => Show1 (T f) where
+>     liftShowsPrec sp _ d (Zero x) =
+>         showsUnaryWith sp "Zero" d x
+>     liftShowsPrec sp sl d (One x) =
+>         showsUnaryWith (liftShowsPrec sp sl) "One" d x
+>     liftShowsPrec sp sl d (Two x y) =
+>         showsBinaryWith sp (liftShowsPrec sp sl) "Two" d x y
+
+-}

third_party/bazel/rules_haskell/examples/transformers/legacy/pre711/Data/Functor/Compose.hs

@@ -0,0 +1,154 @@
+{-# LANGUAGE CPP #-}
+#if __GLASGOW_HASKELL__ >= 702
+{-# LANGUAGE DeriveGeneric #-}
+{-# LANGUAGE EmptyDataDecls #-}
+{-# LANGUAGE StandaloneDeriving #-}
+{-# LANGUAGE Trustworthy #-}
+{-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE TypeOperators #-}
+#endif
+#if __GLASGOW_HASKELL__ >= 706
+{-# LANGUAGE PolyKinds #-}
+#endif
+#if __GLASGOW_HASKELL__ >= 708
+{-# LANGUAGE AutoDeriveTypeable #-}
+{-# LANGUAGE DataKinds #-}
+{-# LANGUAGE DeriveDataTypeable #-}
+{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE KindSignatures #-}
+#endif
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Data.Functor.Compose
+-- Copyright   :  (c) Ross Paterson 2010
+-- License     :  BSD-style (see the file LICENSE)
+--
+-- Maintainer  :  R.Paterson@city.ac.uk
+-- Stability   :  experimental
+-- Portability :  portable
+--
+-- Composition of functors.
+-----------------------------------------------------------------------------
+
+module Data.Functor.Compose (
+    Compose(..),
+  ) where
+
+import Data.Functor.Classes
+#if MIN_VERSION_base(4,12,0)
+import Data.Functor.Contravariant
+#endif
+
+import Control.Applicative
+#if __GLASGOW_HASKELL__ >= 708
+import Data.Data
+#endif
+import Data.Foldable (Foldable(foldMap))
+import Data.Traversable (Traversable(traverse))
+#if __GLASGOW_HASKELL__ >= 702
+import GHC.Generics
+#endif
+
+infixr 9 `Compose`
+
+-- | Right-to-left composition of functors.
+-- The composition of applicative functors is always applicative,
+-- but the composition of monads is not always a monad.
+newtype Compose f g a = Compose { getCompose :: f (g a) }
+
+#if __GLASGOW_HASKELL__ >= 702
+deriving instance Generic (Compose f g a)
+
+instance Functor f => Generic1 (Compose f g) where
+    type Rep1 (Compose f g) =
+      D1 MDCompose
+        (C1 MCCompose
+          (S1 MSCompose (f :.: Rec1 g)))
+    from1 (Compose x) = M1 (M1 (M1 (Comp1 (fmap Rec1 x))))
+    to1 (M1 (M1 (M1 x))) = Compose (fmap unRec1 (unComp1 x))
+
+data MDCompose
+data MCCompose
+data MSCompose
+
+instance Datatype MDCompose where
+    datatypeName _ = "Compose"
+    moduleName   _ = "Data.Functor.Compose"
+# if __GLASGOW_HASKELL__ >= 708
+    isNewtype    _ = True
+# endif
+
+instance Constructor MCCompose where
+    conName     _ = "Compose"
+    conIsRecord _ = True
+
+instance Selector MSCompose where
+    selName _ = "getCompose"
+#endif
+
+#if __GLASGOW_HASKELL__ >= 708
+deriving instance Typeable Compose
+deriving instance (Data (f (g a)), Typeable f, Typeable g, Typeable a)
+               => Data (Compose (f :: * -> *) (g :: * -> *) (a :: *))
+#endif
+
+-- Instances of lifted Prelude classes
+
+instance (Eq1 f, Eq1 g) => Eq1 (Compose f g) where
+    liftEq eq (Compose x) (Compose y) = liftEq (liftEq eq) x y
+
+instance (Ord1 f, Ord1 g) => Ord1 (Compose f g) where
+    liftCompare comp (Compose x) (Compose y) =
+        liftCompare (liftCompare comp) x y
+
+instance (Read1 f, Read1 g) => Read1 (Compose f g) where
+    liftReadsPrec rp rl = readsData $
+        readsUnaryWith (liftReadsPrec rp' rl') "Compose" Compose
+      where
+        rp' = liftReadsPrec rp rl
+        rl' = liftReadList rp rl
+
+instance (Show1 f, Show1 g) => Show1 (Compose f g) where
+    liftShowsPrec sp sl d (Compose x) =
+        showsUnaryWith (liftShowsPrec sp' sl') "Compose" d x
+      where
+        sp' = liftShowsPrec sp sl
+        sl' = liftShowList sp sl
+
+-- Instances of Prelude classes
+
+instance (Eq1 f, Eq1 g, Eq a) => Eq (Compose f g a) where
+    (==) = eq1
+
+instance (Ord1 f, Ord1 g, Ord a) => Ord (Compose f g a) where
+    compare = compare1
+
+instance (Read1 f, Read1 g, Read a) => Read (Compose f g a) where
+    readsPrec = readsPrec1
+
+instance (Show1 f, Show1 g, Show a) => Show (Compose f g a) where
+    showsPrec = showsPrec1
+
+-- Functor instances
+
+instance (Functor f, Functor g) => Functor (Compose f g) where
+    fmap f (Compose x) = Compose (fmap (fmap f) x)
+
+instance (Foldable f, Foldable g) => Foldable (Compose f g) where
+    foldMap f (Compose t) = foldMap (foldMap f) t
+
+instance (Traversable f, Traversable g) => Traversable (Compose f g) where
+    traverse f (Compose t) = Compose <$> traverse (traverse f) t
+
+instance (Applicative f, Applicative g) => Applicative (Compose f g) where
+    pure x = Compose (pure (pure x))
+    Compose f <*> Compose x = Compose ((<*>) <$> f <*> x)
+
+instance (Alternative f, Applicative g) => Alternative (Compose f g) where
+    empty = Compose empty
+    Compose x <|> Compose y = Compose (x <|> y)
+
+#if MIN_VERSION_base(4,12,0)
+instance (Functor f, Contravariant g) => Contravariant (Compose f g) where
+    contramap f (Compose fga) = Compose (fmap (contramap f) fga)
+#endif

third_party/bazel/rules_haskell/examples/transformers/legacy/pre711/Data/Functor/Product.hs

@@ -0,0 +1,156 @@
+{-# LANGUAGE CPP #-}
+#if __GLASGOW_HASKELL__ >= 702
+{-# LANGUAGE DeriveGeneric #-}
+{-# LANGUAGE EmptyDataDecls #-}
+{-# LANGUAGE StandaloneDeriving #-}
+{-# LANGUAGE Trustworthy #-}
+{-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE TypeOperators #-}
+#endif
+#if __GLASGOW_HASKELL__ >= 706
+{-# LANGUAGE PolyKinds #-}
+#endif
+#if __GLASGOW_HASKELL__ >= 708
+{-# LANGUAGE AutoDeriveTypeable #-}
+{-# LANGUAGE DataKinds #-}
+{-# LANGUAGE DeriveDataTypeable #-}
+{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE KindSignatures #-}
+#endif
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Data.Functor.Product
+-- Copyright   :  (c) Ross Paterson 2010
+-- License     :  BSD-style (see the file LICENSE)
+--
+-- Maintainer  :  R.Paterson@city.ac.uk
+-- Stability   :  experimental
+-- Portability :  portable
+--
+-- Products, lifted to functors.
+-----------------------------------------------------------------------------
+
+module Data.Functor.Product (
+    Product(..),
+  ) where
+
+import Control.Applicative
+import Control.Monad (MonadPlus(..))
+import Control.Monad.Fix (MonadFix(..))
+#if MIN_VERSION_base(4,4,0)
+import Control.Monad.Zip (MonadZip(mzipWith))
+#endif
+#if __GLASGOW_HASKELL__ >= 708
+import Data.Data
+#endif
+import Data.Foldable (Foldable(foldMap))
+import Data.Functor.Classes
+#if MIN_VERSION_base(4,12,0)
+import Data.Functor.Contravariant
+#endif
+import Data.Monoid (mappend)
+import Data.Traversable (Traversable(traverse))
+#if __GLASGOW_HASKELL__ >= 702
+import GHC.Generics
+#endif
+
+-- | Lifted product of functors.
+data Product f g a = Pair (f a) (g a)
+
+#if __GLASGOW_HASKELL__ >= 702
+deriving instance Generic (Product f g a)
+
+instance Generic1 (Product f g) where
+    type Rep1 (Product f g) =
+      D1 MDProduct
+        (C1 MCPair
+          (S1 NoSelector (Rec1 f) :*: S1 NoSelector (Rec1 g)))
+    from1 (Pair f g) = M1 (M1 (M1 (Rec1 f) :*: M1 (Rec1 g)))
+    to1 (M1 (M1 (M1 f :*: M1 g))) = Pair (unRec1 f) (unRec1 g)
+
+data MDProduct
+data MCPair
+
+instance Datatype MDProduct where
+    datatypeName _ = "Product"
+    moduleName   _ = "Data.Functor.Product"
+
+instance Constructor MCPair where
+    conName _ = "Pair"
+#endif
+
+#if __GLASGOW_HASKELL__ >= 708
+deriving instance Typeable Product
+deriving instance (Data (f a), Data (g a), Typeable f, Typeable g, Typeable a)
+               => Data (Product (f :: * -> *) (g :: * -> *) (a :: *))
+#endif
+
+instance (Eq1 f, Eq1 g) => Eq1 (Product f g) where
+    liftEq eq (Pair x1 y1) (Pair x2 y2) = liftEq eq x1 x2 && liftEq eq y1 y2
+
+instance (Ord1 f, Ord1 g) => Ord1 (Product f g) where
+    liftCompare comp (Pair x1 y1) (Pair x2 y2) =
+        liftCompare comp x1 x2 `mappend` liftCompare comp y1 y2
+
+instance (Read1 f, Read1 g) => Read1 (Product f g) where
+    liftReadsPrec rp rl = readsData $
+        readsBinaryWith (liftReadsPrec rp rl) (liftReadsPrec rp rl) "Pair" Pair
+
+instance (Show1 f, Show1 g) => Show1 (Product f g) where
+    liftShowsPrec sp sl d (Pair x y) =
+        showsBinaryWith (liftShowsPrec sp sl) (liftShowsPrec sp sl) "Pair" d x y
+
+instance (Eq1 f, Eq1 g, Eq a) => Eq (Product f g a)
+    where (==) = eq1
+instance (Ord1 f, Ord1 g, Ord a) => Ord (Product f g a) where
+    compare = compare1
+instance (Read1 f, Read1 g, Read a) => Read (Product f g a) where
+    readsPrec = readsPrec1
+instance (Show1 f, Show1 g, Show a) => Show (Product f g a) where
+    showsPrec = showsPrec1
+
+instance (Functor f, Functor g) => Functor (Product f g) where
+    fmap f (Pair x y) = Pair (fmap f x) (fmap f y)
+
+instance (Foldable f, Foldable g) => Foldable (Product f g) where
+    foldMap f (Pair x y) = foldMap f x `mappend` foldMap f y
+
+instance (Traversable f, Traversable g) => Traversable (Product f g) where
+    traverse f (Pair x y) = Pair <$> traverse f x <*> traverse f y
+
+instance (Applicative f, Applicative g) => Applicative (Product f g) where
+    pure x = Pair (pure x) (pure x)
+    Pair f g <*> Pair x y = Pair (f <*> x) (g <*> y)
+
+instance (Alternative f, Alternative g) => Alternative (Product f g) where
+    empty = Pair empty empty
+    Pair x1 y1 <|> Pair x2 y2 = Pair (x1 <|> x2) (y1 <|> y2)
+
+instance (Monad f, Monad g) => Monad (Product f g) where
+#if !(MIN_VERSION_base(4,8,0))
+    return x = Pair (return x) (return x)
+#endif
+    Pair m n >>= f = Pair (m >>= fstP . f) (n >>= sndP . f)
+      where
+        fstP (Pair a _) = a
+        sndP (Pair _ b) = b
+
+instance (MonadPlus f, MonadPlus g) => MonadPlus (Product f g) where
+    mzero = Pair mzero mzero
+    Pair x1 y1 `mplus` Pair x2 y2 = Pair (x1 `mplus` x2) (y1 `mplus` y2)
+
+instance (MonadFix f, MonadFix g) => MonadFix (Product f g) where
+    mfix f = Pair (mfix (fstP . f)) (mfix (sndP . f))
+      where
+        fstP (Pair a _) = a
+        sndP (Pair _ b) = b
+
+#if MIN_VERSION_base(4,4,0)
+instance (MonadZip f, MonadZip g) => MonadZip (Product f g) where
+    mzipWith f (Pair x1 y1) (Pair x2 y2) = Pair (mzipWith f x1 x2) (mzipWith f y1 y2)
+#endif
+
+#if MIN_VERSION_base(4,12,0)
+instance (Contravariant f, Contravariant g) => Contravariant (Product f g) where
+    contramap f (Pair a b) = Pair (contramap f a) (contramap f b)
+#endif

third_party/bazel/rules_haskell/examples/transformers/legacy/pre711/Data/Functor/Sum.hs

@@ -0,0 +1,136 @@
+{-# LANGUAGE CPP #-}
+#if __GLASGOW_HASKELL__ >= 702
+{-# LANGUAGE DeriveGeneric #-}
+{-# LANGUAGE EmptyDataDecls #-}
+{-# LANGUAGE StandaloneDeriving #-}
+{-# LANGUAGE Trustworthy #-}
+{-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE TypeOperators #-}
+#endif
+#if __GLASGOW_HASKELL__ >= 706
+{-# LANGUAGE PolyKinds #-}
+#endif
+#if __GLASGOW_HASKELL__ >= 708
+{-# LANGUAGE AutoDeriveTypeable #-}
+{-# LANGUAGE DataKinds #-}
+{-# LANGUAGE DeriveDataTypeable #-}
+{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE KindSignatures #-}
+#endif
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Data.Functor.Sum
+-- Copyright   :  (c) Ross Paterson 2014
+-- License     :  BSD-style (see the file LICENSE)
+--
+-- Maintainer  :  R.Paterson@city.ac.uk
+-- Stability   :  experimental
+-- Portability :  portable
+--
+-- Sums, lifted to functors.
+-----------------------------------------------------------------------------
+
+module Data.Functor.Sum (
+    Sum(..),
+  ) where
+
+import Control.Applicative
+#if __GLASGOW_HASKELL__ >= 708
+import Data.Data
+#endif
+import Data.Foldable (Foldable(foldMap))
+import Data.Functor.Classes
+#if MIN_VERSION_base(4,12,0)
+import Data.Functor.Contravariant
+#endif
+import Data.Monoid (mappend)
+import Data.Traversable (Traversable(traverse))
+#if __GLASGOW_HASKELL__ >= 702
+import GHC.Generics
+#endif
+
+-- | Lifted sum of functors.
+data Sum f g a = InL (f a) | InR (g a)
+
+#if __GLASGOW_HASKELL__ >= 702
+deriving instance Generic (Sum f g a)
+
+instance Generic1 (Sum f g) where
+    type Rep1 (Sum f g) =
+      D1 MDSum (C1 MCInL (S1 NoSelector (Rec1 f))
+            :+: C1 MCInR (S1 NoSelector (Rec1 g)))
+    from1 (InL f) = M1 (L1 (M1 (M1 (Rec1 f))))
+    from1 (InR g) = M1 (R1 (M1 (M1 (Rec1 g))))
+    to1 (M1 (L1 (M1 (M1 f)))) = InL (unRec1 f)
+    to1 (M1 (R1 (M1 (M1 g)))) = InR (unRec1 g)
+
+data MDSum
+data MCInL
+data MCInR
+
+instance Datatype MDSum where
+    datatypeName _ = "Sum"
+    moduleName   _ = "Data.Functor.Sum"
+
+instance Constructor MCInL where
+    conName _ = "InL"
+
+instance Constructor MCInR where
+    conName _ = "InR"
+#endif
+
+#if __GLASGOW_HASKELL__ >= 708
+deriving instance Typeable Sum
+deriving instance (Data (f a), Data (g a), Typeable f, Typeable g, Typeable a)
+               => Data (Sum (f :: * -> *) (g :: * -> *) (a :: *))
+#endif
+
+instance (Eq1 f, Eq1 g) => Eq1 (Sum f g) where
+    liftEq eq (InL x1) (InL x2) = liftEq eq x1 x2
+    liftEq _ (InL _) (InR _) = False
+    liftEq _ (InR _) (InL _) = False
+    liftEq eq (InR y1) (InR y2) = liftEq eq y1 y2
+
+instance (Ord1 f, Ord1 g) => Ord1 (Sum f g) where
+    liftCompare comp (InL x1) (InL x2) = liftCompare comp x1 x2
+    liftCompare _ (InL _) (InR _) = LT
+    liftCompare _ (InR _) (InL _) = GT
+    liftCompare comp (InR y1) (InR y2) = liftCompare comp y1 y2
+
+instance (Read1 f, Read1 g) => Read1 (Sum f g) where
+    liftReadsPrec rp rl = readsData $
+        readsUnaryWith (liftReadsPrec rp rl) "InL" InL `mappend`
+        readsUnaryWith (liftReadsPrec rp rl) "InR" InR
+
+instance (Show1 f, Show1 g) => Show1 (Sum f g) where
+    liftShowsPrec sp sl d (InL x) =
+        showsUnaryWith (liftShowsPrec sp sl) "InL" d x
+    liftShowsPrec sp sl d (InR y) =
+        showsUnaryWith (liftShowsPrec sp sl) "InR" d y
+
+instance (Eq1 f, Eq1 g, Eq a) => Eq (Sum f g a) where
+    (==) = eq1
+instance (Ord1 f, Ord1 g, Ord a) => Ord (Sum f g a) where
+    compare = compare1
+instance (Read1 f, Read1 g, Read a) => Read (Sum f g a) where
+    readsPrec = readsPrec1
+instance (Show1 f, Show1 g, Show a) => Show (Sum f g a) where
+    showsPrec = showsPrec1
+
+instance (Functor f, Functor g) => Functor (Sum f g) where
+    fmap f (InL x) = InL (fmap f x)
+    fmap f (InR y) = InR (fmap f y)
+
+instance (Foldable f, Foldable g) => Foldable (Sum f g) where
+    foldMap f (InL x) = foldMap f x
+    foldMap f (InR y) = foldMap f y
+
+instance (Traversable f, Traversable g) => Traversable (Sum f g) where
+    traverse f (InL x) = InL <$> traverse f x
+    traverse f (InR y) = InR <$> traverse f y
+
+#if MIN_VERSION_base(4,12,0)
+instance (Contravariant f, Contravariant g) => Contravariant (Sum f g) where
+    contramap f (InL xs) = InL (contramap f xs)
+    contramap f (InR ys) = InR (contramap f ys)
+#endif

third_party/bazel/rules_haskell/examples/transformers/transformers.cabal

@@ -0,0 +1,91 @@
+name:         transformers
+version:      0.5.6.2
+license:      BSD3
+license-file: LICENSE
+author:       Andy Gill, Ross Paterson
+maintainer:   Ross Paterson <R.Paterson@city.ac.uk>
+bug-reports:  http://hub.darcs.net/ross/transformers/issues
+category:     Control
+synopsis:     Concrete functor and monad transformers
+description:
+    A portable library of functor and monad transformers, inspired by
+    the paper
+    .
+    * \"Functional Programming with Overloading and Higher-Order
+    Polymorphism\", by Mark P Jones,
+    in /Advanced School of Functional Programming/, 1995
+    (<http://web.cecs.pdx.edu/~mpj/pubs/springschool.html>).
+    .
+    This package contains:
+    .
+    * the monad transformer class (in "Control.Monad.Trans.Class")
+    .
+    * concrete functor and monad transformers, each with associated
+      operations and functions to lift operations associated with other
+      transformers.
+    .
+    The package can be used on its own in portable Haskell code, in
+    which case operations need to be manually lifted through transformer
+    stacks (see "Control.Monad.Trans.Class" for some examples).
+    Alternatively, it can be used with the non-portable monad classes in
+    the @mtl@ or @monads-tf@ packages, which automatically lift operations
+    introduced by monad transformers through other transformers.
+build-type: Simple
+extra-source-files:
+    changelog
+cabal-version: >= 1.6
+
+source-repository head
+  type: darcs
+  location: http://hub.darcs.net/ross/transformers
+
+library
+  build-depends: base >= 2 && < 6
+  hs-source-dirs: .
+  if !impl(ghc>=7.9)
+    -- Data.Functor.Identity was moved into base-4.8.0.0 (GHC 7.10)
+    -- see also https://ghc.haskell.org/trac/ghc/ticket/9664
+    -- NB: using impl(ghc>=7.9) instead of fragile Cabal flags
+    hs-source-dirs: legacy/pre709
+    exposed-modules: Data.Functor.Identity
+  if !impl(ghc>=7.11)
+    -- modules moved into base-4.9.0 (GHC 8.0)
+    -- see https://ghc.haskell.org/trac/ghc/ticket/10773
+    -- see https://ghc.haskell.org/trac/ghc/ticket/11135
+    hs-source-dirs: legacy/pre711
+    exposed-modules:
+      Control.Monad.IO.Class
+      Data.Functor.Classes
+      Data.Functor.Compose
+      Data.Functor.Product
+      Data.Functor.Sum
+  if impl(ghc>=7.2 && <7.5)
+    -- Prior to GHC 7.5, GHC.Generics lived in ghc-prim
+    build-depends: ghc-prim
+  exposed-modules:
+    Control.Applicative.Backwards
+    Control.Applicative.Lift
+    Control.Monad.Signatures
+    Control.Monad.Trans.Accum
+    Control.Monad.Trans.Class
+    Control.Monad.Trans.Cont
+    Control.Monad.Trans.Except
+    Control.Monad.Trans.Error
+    Control.Monad.Trans.Identity
+    Control.Monad.Trans.List
+    Control.Monad.Trans.Maybe
+    Control.Monad.Trans.Reader
+    Control.Monad.Trans.RWS
+    Control.Monad.Trans.RWS.CPS
+    Control.Monad.Trans.RWS.Lazy
+    Control.Monad.Trans.RWS.Strict
+    Control.Monad.Trans.Select
+    Control.Monad.Trans.State
+    Control.Monad.Trans.State.Lazy
+    Control.Monad.Trans.State.Strict
+    Control.Monad.Trans.Writer
+    Control.Monad.Trans.Writer.CPS
+    Control.Monad.Trans.Writer.Lazy
+    Control.Monad.Trans.Writer.Strict
+    Data.Functor.Constant
+    Data.Functor.Reverse

third_party/bazel/rules_haskell/examples/vector/BUILD.bazel

@@ -0,0 +1,38 @@
+load(
+    "@io_tweag_rules_haskell//haskell:haskell.bzl",
+    "haskell_cc_import",
+    "haskell_library",
+    "haskell_toolchain_library",
+)
+
+haskell_toolchain_library(name = "base")
+
+haskell_toolchain_library(name = "deepseq")
+
+haskell_toolchain_library(name = "ghc-prim")
+
+haskell_toolchain_library(name = "primitive")
+
+haskell_toolchain_library(name = "semigroups")
+
+haskell_library(
+    name = "vector",
+    testonly = 1,
+    srcs = glob(["Data/**/*.*hs"]),
+    compiler_flags = [
+        "-Iexternal/io_tweag_rules_haskell_examples/vector/include",
+        "-Iexternal/io_tweag_rules_haskell_examples/vector/internal",
+    ],
+    extra_srcs = [
+        "include/vector.h",
+        "internal/unbox-tuple-instances",
+    ],
+    version = "0",
+    visibility = ["//visibility:public"],
+    deps = [
+        ":base",
+        ":deepseq",
+        ":ghc-prim",
+        "//primitive",
+    ],
+)

third_party/bazel/rules_haskell/examples/vector/Data/Vector/Fusion/Bundle.hs

@@ -0,0 +1,655 @@
+{-# LANGUAGE CPP, FlexibleInstances, Rank2Types, BangPatterns #-}
+
+-- |
+-- Module      : Data.Vector.Fusion.Bundle
+-- Copyright   : (c) Roman Leshchinskiy 2008-2010
+-- License     : BSD-style
+--
+-- Maintainer  : Roman Leshchinskiy <rl@cse.unsw.edu.au>
+-- Stability   : experimental
+-- Portability : non-portable
+--
+-- Bundles for stream fusion
+--
+
+module Data.Vector.Fusion.Bundle (
+  -- * Types
+  Step(..), Chunk(..), Bundle, MBundle,
+
+  -- * In-place markers
+  inplace,
+
+  -- * Size hints
+  size, sized,
+
+  -- * Length information
+  length, null,
+
+  -- * Construction
+  empty, singleton, cons, snoc, replicate, generate, (++),
+
+  -- * Accessing individual elements
+  head, last, (!!), (!?),
+
+  -- * Substreams
+  slice, init, tail, take, drop,
+
+  -- * Mapping
+  map, concatMap, flatten, unbox,
+
+  -- * Zipping
+  indexed, indexedR,
+  zipWith, zipWith3, zipWith4, zipWith5, zipWith6,
+  zip, zip3, zip4, zip5, zip6,
+
+  -- * Filtering
+  filter, takeWhile, dropWhile,
+
+  -- * Searching
+  elem, notElem, find, findIndex,
+
+  -- * Folding
+  foldl, foldl1, foldl', foldl1', foldr, foldr1,
+
+  -- * Specialised folds
+  and, or,
+
+  -- * Unfolding
+  unfoldr, unfoldrN, iterateN,
+
+  -- * Scans
+  prescanl, prescanl',
+  postscanl, postscanl',
+  scanl, scanl',
+  scanl1, scanl1',
+
+  -- * Enumerations
+  enumFromStepN, enumFromTo, enumFromThenTo,
+
+  -- * Conversions
+  toList, fromList, fromListN, unsafeFromList, lift,
+  fromVector, reVector, fromVectors, concatVectors,
+
+  -- * Monadic combinators
+  mapM, mapM_, zipWithM, zipWithM_, filterM, foldM, fold1M, foldM', fold1M',
+
+  eq, cmp, eqBy, cmpBy
+) where
+
+import Data.Vector.Generic.Base ( Vector )
+import Data.Vector.Fusion.Bundle.Size
+import Data.Vector.Fusion.Util
+import Data.Vector.Fusion.Stream.Monadic ( Stream(..), Step(..) )
+import Data.Vector.Fusion.Bundle.Monadic ( Chunk(..) )
+import qualified Data.Vector.Fusion.Bundle.Monadic as M
+import qualified Data.Vector.Fusion.Stream.Monadic as S
+
+import Prelude hiding ( length, null,
+                        replicate, (++),
+                        head, last, (!!),
+                        init, tail, take, drop,
+                        map, concatMap,
+                        zipWith, zipWith3, zip, zip3,
+                        filter, takeWhile, dropWhile,
+                        elem, notElem,
+                        foldl, foldl1, foldr, foldr1,
+                        and, or,
+                        scanl, scanl1,
+                        enumFromTo, enumFromThenTo,
+                        mapM, mapM_ )
+
+#if MIN_VERSION_base(4,9,0)
+import Data.Functor.Classes (Eq1 (..), Ord1 (..))
+#endif
+
+import GHC.Base ( build )
+
+-- Data.Vector.Internal.Check is unused
+#define NOT_VECTOR_MODULE
+#include "vector.h"
+
+-- | The type of pure streams
+type Bundle = M.Bundle Id
+
+-- | Alternative name for monadic streams
+type MBundle = M.Bundle
+
+inplace :: (forall m. Monad m => S.Stream m a -> S.Stream m b)
+        -> (Size -> Size) -> Bundle v a -> Bundle v b
+{-# INLINE_FUSED inplace #-}
+inplace f g b = b `seq` M.fromStream (f (M.elements b)) (g (M.size b))
+
+{-# RULES
+
+"inplace/inplace [Vector]"
+  forall (f1 :: forall m. Monad m => S.Stream m a -> S.Stream m a)
+         (f2 :: forall m. Monad m => S.Stream m a -> S.Stream m a)
+         g1 g2 s.
+  inplace f1 g1 (inplace f2 g2 s) = inplace (f1 . f2) (g1 . g2) s   #-}
+
+
+
+-- | Convert a pure stream to a monadic stream
+lift :: Monad m => Bundle v a -> M.Bundle m v a
+{-# INLINE_FUSED lift #-}
+lift (M.Bundle (Stream step s) (Stream vstep t) v sz)
+    = M.Bundle (Stream (return . unId . step) s)
+               (Stream (return . unId . vstep) t) v sz
+
+-- | 'Size' hint of a 'Bundle'
+size :: Bundle v a -> Size
+{-# INLINE size #-}
+size = M.size
+
+-- | Attach a 'Size' hint to a 'Bundle'
+sized :: Bundle v a -> Size -> Bundle v a
+{-# INLINE sized #-}
+sized = M.sized
+
+-- Length
+-- ------
+
+-- | Length of a 'Bundle'
+length :: Bundle v a -> Int
+{-# INLINE length #-}
+length = unId . M.length
+
+-- | Check if a 'Bundle' is empty
+null :: Bundle v a -> Bool
+{-# INLINE null #-}
+null = unId . M.null
+
+-- Construction
+-- ------------
+
+-- | Empty 'Bundle'
+empty :: Bundle v a
+{-# INLINE empty #-}
+empty = M.empty
+
+-- | Singleton 'Bundle'
+singleton :: a -> Bundle v a
+{-# INLINE singleton #-}
+singleton = M.singleton
+
+-- | Replicate a value to a given length
+replicate :: Int -> a -> Bundle v a
+{-# INLINE replicate #-}
+replicate = M.replicate
+
+-- | Generate a stream from its indices
+generate :: Int -> (Int -> a) -> Bundle v a
+{-# INLINE generate #-}
+generate = M.generate
+
+-- | Prepend an element
+cons :: a -> Bundle v a -> Bundle v a
+{-# INLINE cons #-}
+cons = M.cons
+
+-- | Append an element
+snoc :: Bundle v a -> a -> Bundle v a
+{-# INLINE snoc #-}
+snoc = M.snoc
+
+infixr 5 ++
+-- | Concatenate two 'Bundle's
+(++) :: Bundle v a -> Bundle v a -> Bundle v a
+{-# INLINE (++) #-}
+(++) = (M.++)
+
+-- Accessing elements
+-- ------------------
+
+-- | First element of the 'Bundle' or error if empty
+head :: Bundle v a -> a
+{-# INLINE head #-}
+head = unId . M.head
+
+-- | Last element of the 'Bundle' or error if empty
+last :: Bundle v a -> a
+{-# INLINE last #-}
+last = unId . M.last
+
+infixl 9 !!
+-- | Element at the given position
+(!!) :: Bundle v a -> Int -> a
+{-# INLINE (!!) #-}
+s !! i = unId (s M.!! i)
+
+infixl 9 !?
+-- | Element at the given position or 'Nothing' if out of bounds
+(!?) :: Bundle v a -> Int -> Maybe a
+{-# INLINE (!?) #-}
+s !? i = unId (s M.!? i)
+
+-- Substreams
+-- ----------
+
+-- | Extract a substream of the given length starting at the given position.
+slice :: Int   -- ^ starting index
+      -> Int   -- ^ length
+      -> Bundle v a
+      -> Bundle v a
+{-# INLINE slice #-}
+slice = M.slice
+
+-- | All but the last element
+init :: Bundle v a -> Bundle v a
+{-# INLINE init #-}
+init = M.init
+
+-- | All but the first element
+tail :: Bundle v a -> Bundle v a
+{-# INLINE tail #-}
+tail = M.tail
+
+-- | The first @n@ elements
+take :: Int -> Bundle v a -> Bundle v a
+{-# INLINE take #-}
+take = M.take
+
+-- | All but the first @n@ elements
+drop :: Int -> Bundle v a -> Bundle v a
+{-# INLINE drop #-}
+drop = M.drop
+
+-- Mapping
+-- ---------------
+
+-- | Map a function over a 'Bundle'
+map :: (a -> b) -> Bundle v a -> Bundle v b
+{-# INLINE map #-}
+map = M.map
+
+unbox :: Bundle v (Box a) -> Bundle v a
+{-# INLINE unbox #-}
+unbox = M.unbox
+
+concatMap :: (a -> Bundle v b) -> Bundle v a -> Bundle v b
+{-# INLINE concatMap #-}
+concatMap = M.concatMap
+
+-- Zipping
+-- -------
+
+-- | Pair each element in a 'Bundle' with its index
+indexed :: Bundle v a -> Bundle v (Int,a)
+{-# INLINE indexed #-}
+indexed = M.indexed
+
+-- | Pair each element in a 'Bundle' with its index, starting from the right
+-- and counting down
+indexedR :: Int -> Bundle v a -> Bundle v (Int,a)
+{-# INLINE_FUSED indexedR #-}
+indexedR = M.indexedR
+
+-- | Zip two 'Bundle's with the given function
+zipWith :: (a -> b -> c) -> Bundle v a -> Bundle v b -> Bundle v c
+{-# INLINE zipWith #-}
+zipWith = M.zipWith
+
+-- | Zip three 'Bundle's with the given function
+zipWith3 :: (a -> b -> c -> d) -> Bundle v a -> Bundle v b -> Bundle v c -> Bundle v d
+{-# INLINE zipWith3 #-}
+zipWith3 = M.zipWith3
+
+zipWith4 :: (a -> b -> c -> d -> e)
+                    -> Bundle v a -> Bundle v b -> Bundle v c -> Bundle v d
+                    -> Bundle v e
+{-# INLINE zipWith4 #-}
+zipWith4 = M.zipWith4
+
+zipWith5 :: (a -> b -> c -> d -> e -> f)
+                    -> Bundle v a -> Bundle v b -> Bundle v c -> Bundle v d
+                    -> Bundle v e -> Bundle v f
+{-# INLINE zipWith5 #-}
+zipWith5 = M.zipWith5
+
+zipWith6 :: (a -> b -> c -> d -> e -> f -> g)
+                    -> Bundle v a -> Bundle v b -> Bundle v c -> Bundle v d
+                    -> Bundle v e -> Bundle v f -> Bundle v g
+{-# INLINE zipWith6 #-}
+zipWith6 = M.zipWith6
+
+zip :: Bundle v a -> Bundle v b -> Bundle v (a,b)
+{-# INLINE zip #-}
+zip = M.zip
+
+zip3 :: Bundle v a -> Bundle v b -> Bundle v c -> Bundle v (a,b,c)
+{-# INLINE zip3 #-}
+zip3 = M.zip3
+
+zip4 :: Bundle v a -> Bundle v b -> Bundle v c -> Bundle v d
+                -> Bundle v (a,b,c,d)
+{-# INLINE zip4 #-}
+zip4 = M.zip4
+
+zip5 :: Bundle v a -> Bundle v b -> Bundle v c -> Bundle v d
+                -> Bundle v e -> Bundle v (a,b,c,d,e)
+{-# INLINE zip5 #-}
+zip5 = M.zip5
+
+zip6 :: Bundle v a -> Bundle v b -> Bundle v c -> Bundle v d
+                -> Bundle v e -> Bundle v f -> Bundle v (a,b,c,d,e,f)
+{-# INLINE zip6 #-}
+zip6 = M.zip6
+
+-- Filtering
+-- ---------
+
+-- | Drop elements which do not satisfy the predicate
+filter :: (a -> Bool) -> Bundle v a -> Bundle v a
+{-# INLINE filter #-}
+filter = M.filter
+
+-- | Longest prefix of elements that satisfy the predicate
+takeWhile :: (a -> Bool) -> Bundle v a -> Bundle v a
+{-# INLINE takeWhile #-}
+takeWhile = M.takeWhile
+
+-- | Drop the longest prefix of elements that satisfy the predicate
+dropWhile :: (a -> Bool) -> Bundle v a -> Bundle v a
+{-# INLINE dropWhile #-}
+dropWhile = M.dropWhile
+
+-- Searching
+-- ---------
+
+infix 4 `elem`
+-- | Check whether the 'Bundle' contains an element
+elem :: Eq a => a -> Bundle v a -> Bool
+{-# INLINE elem #-}
+elem x = unId . M.elem x
+
+infix 4 `notElem`
+-- | Inverse of `elem`
+notElem :: Eq a => a -> Bundle v a -> Bool
+{-# INLINE notElem #-}
+notElem x = unId . M.notElem x
+
+-- | Yield 'Just' the first element matching the predicate or 'Nothing' if no
+-- such element exists.
+find :: (a -> Bool) -> Bundle v a -> Maybe a
+{-# INLINE find #-}
+find f = unId . M.find f
+
+-- | Yield 'Just' the index of the first element matching the predicate or
+-- 'Nothing' if no such element exists.
+findIndex :: (a -> Bool) -> Bundle v a -> Maybe Int
+{-# INLINE findIndex #-}
+findIndex f = unId . M.findIndex f
+
+-- Folding
+-- -------
+
+-- | Left fold
+foldl :: (a -> b -> a) -> a -> Bundle v b -> a
+{-# INLINE foldl #-}
+foldl f z = unId . M.foldl f z
+
+-- | Left fold on non-empty 'Bundle's
+foldl1 :: (a -> a -> a) -> Bundle v a -> a
+{-# INLINE foldl1 #-}
+foldl1 f = unId . M.foldl1 f
+
+-- | Left fold with strict accumulator
+foldl' :: (a -> b -> a) -> a -> Bundle v b -> a
+{-# INLINE foldl' #-}
+foldl' f z = unId . M.foldl' f z
+
+-- | Left fold on non-empty 'Bundle's with strict accumulator
+foldl1' :: (a -> a -> a) -> Bundle v a -> a
+{-# INLINE foldl1' #-}
+foldl1' f = unId . M.foldl1' f
+
+-- | Right fold
+foldr :: (a -> b -> b) -> b -> Bundle v a -> b
+{-# INLINE foldr #-}
+foldr f z = unId . M.foldr f z
+
+-- | Right fold on non-empty 'Bundle's
+foldr1 :: (a -> a -> a) -> Bundle v a -> a
+{-# INLINE foldr1 #-}
+foldr1 f = unId . M.foldr1 f
+
+-- Specialised folds
+-- -----------------
+
+and :: Bundle v Bool -> Bool
+{-# INLINE and #-}
+and = unId . M.and
+
+or :: Bundle v Bool -> Bool
+{-# INLINE or #-}
+or = unId . M.or
+
+-- Unfolding
+-- ---------
+
+-- | Unfold
+unfoldr :: (s -> Maybe (a, s)) -> s -> Bundle v a
+{-# INLINE unfoldr #-}
+unfoldr = M.unfoldr
+
+-- | Unfold at most @n@ elements
+unfoldrN :: Int -> (s -> Maybe (a, s)) -> s -> Bundle v a
+{-# INLINE unfoldrN #-}
+unfoldrN = M.unfoldrN
+
+-- | Apply function n-1 times to value. Zeroth element is original value.
+iterateN :: Int -> (a -> a) -> a -> Bundle v a
+{-# INLINE iterateN #-}
+iterateN = M.iterateN
+
+-- Scans
+-- -----
+
+-- | Prefix scan
+prescanl :: (a -> b -> a) -> a -> Bundle v b -> Bundle v a
+{-# INLINE prescanl #-}
+prescanl = M.prescanl
+
+-- | Prefix scan with strict accumulator
+prescanl' :: (a -> b -> a) -> a -> Bundle v b -> Bundle v a
+{-# INLINE prescanl' #-}
+prescanl' = M.prescanl'
+
+-- | Suffix scan
+postscanl :: (a -> b -> a) -> a -> Bundle v b -> Bundle v a
+{-# INLINE postscanl #-}
+postscanl = M.postscanl
+
+-- | Suffix scan with strict accumulator
+postscanl' :: (a -> b -> a) -> a -> Bundle v b -> Bundle v a
+{-# INLINE postscanl' #-}
+postscanl' = M.postscanl'
+
+-- | Haskell-style scan
+scanl :: (a -> b -> a) -> a -> Bundle v b -> Bundle v a
+{-# INLINE scanl #-}
+scanl = M.scanl
+
+-- | Haskell-style scan with strict accumulator
+scanl' :: (a -> b -> a) -> a -> Bundle v b -> Bundle v a
+{-# INLINE scanl' #-}
+scanl' = M.scanl'
+
+-- | Scan over a non-empty 'Bundle'
+scanl1 :: (a -> a -> a) -> Bundle v a -> Bundle v a
+{-# INLINE scanl1 #-}
+scanl1 = M.scanl1
+
+-- | Scan over a non-empty 'Bundle' with a strict accumulator
+scanl1' :: (a -> a -> a) -> Bundle v a -> Bundle v a
+{-# INLINE scanl1' #-}
+scanl1' = M.scanl1'
+
+
+-- Comparisons
+-- -----------
+
+-- | Check if two 'Bundle's are equal
+eq :: (Eq a) => Bundle v a -> Bundle v a -> Bool
+{-# INLINE eq #-}
+eq = eqBy (==)
+
+eqBy :: (a -> b -> Bool) -> Bundle v a -> Bundle v b -> Bool
+{-# INLINE eqBy #-}
+eqBy e x y = unId (M.eqBy e x y)
+
+-- | Lexicographically compare two 'Bundle's
+cmp :: (Ord a) => Bundle v a -> Bundle v a -> Ordering
+{-# INLINE cmp #-}
+cmp = cmpBy compare
+
+cmpBy :: (a ->  b -> Ordering) -> Bundle v a -> Bundle v b -> Ordering
+{-# INLINE cmpBy #-}
+cmpBy c x y = unId (M.cmpBy c x y)
+
+instance Eq a => Eq (M.Bundle Id v a) where
+  {-# INLINE (==) #-}
+  (==) = eq
+
+instance Ord a => Ord (M.Bundle Id v a) where
+  {-# INLINE compare #-}
+  compare = cmp
+
+#if MIN_VERSION_base(4,9,0)
+instance Eq1 (M.Bundle Id v) where
+  {-# INLINE liftEq #-}
+  liftEq = eqBy
+
+instance Ord1 (M.Bundle Id v) where
+  {-# INLINE liftCompare #-}
+  liftCompare = cmpBy
+#endif
+
+-- Monadic combinators
+-- -------------------
+
+-- | Apply a monadic action to each element of the stream, producing a monadic
+-- stream of results
+mapM :: Monad m => (a -> m b) -> Bundle v a -> M.Bundle m v b
+{-# INLINE mapM #-}
+mapM f = M.mapM f . lift
+
+-- | Apply a monadic action to each element of the stream
+mapM_ :: Monad m => (a -> m b) -> Bundle v a -> m ()
+{-# INLINE mapM_ #-}
+mapM_ f = M.mapM_ f . lift
+
+zipWithM :: Monad m => (a -> b -> m c) -> Bundle v a -> Bundle v b -> M.Bundle m v c
+{-# INLINE zipWithM #-}
+zipWithM f as bs = M.zipWithM f (lift as) (lift bs)
+
+zipWithM_ :: Monad m => (a -> b -> m c) -> Bundle v a -> Bundle v b -> m ()
+{-# INLINE zipWithM_ #-}
+zipWithM_ f as bs = M.zipWithM_ f (lift as) (lift bs)
+
+-- | Yield a monadic stream of elements that satisfy the monadic predicate
+filterM :: Monad m => (a -> m Bool) -> Bundle v a -> M.Bundle m v a
+{-# INLINE filterM #-}
+filterM f = M.filterM f . lift
+
+-- | Monadic fold
+foldM :: Monad m => (a -> b -> m a) -> a -> Bundle v b -> m a
+{-# INLINE foldM #-}
+foldM m z = M.foldM m z . lift
+
+-- | Monadic fold over non-empty stream
+fold1M :: Monad m => (a -> a -> m a) -> Bundle v a -> m a
+{-# INLINE fold1M #-}
+fold1M m = M.fold1M m . lift
+
+-- | Monadic fold with strict accumulator
+foldM' :: Monad m => (a -> b -> m a) -> a -> Bundle v b -> m a
+{-# INLINE foldM' #-}
+foldM' m z = M.foldM' m z . lift
+
+-- | Monad fold over non-empty stream with strict accumulator
+fold1M' :: Monad m => (a -> a -> m a) -> Bundle v a -> m a
+{-# INLINE fold1M' #-}
+fold1M' m = M.fold1M' m . lift
+
+-- Enumerations
+-- ------------
+
+-- | Yield a 'Bundle' of the given length containing the values @x@, @x+y@,
+-- @x+y+y@ etc.
+enumFromStepN :: Num a => a -> a -> Int -> Bundle v a
+{-# INLINE enumFromStepN #-}
+enumFromStepN = M.enumFromStepN
+
+-- | Enumerate values
+--
+-- /WARNING:/ This operations can be very inefficient. If at all possible, use
+-- 'enumFromStepN' instead.
+enumFromTo :: Enum a => a -> a -> Bundle v a
+{-# INLINE enumFromTo #-}
+enumFromTo = M.enumFromTo
+
+-- | Enumerate values with a given step.
+--
+-- /WARNING:/ This operations is very inefficient. If at all possible, use
+-- 'enumFromStepN' instead.
+enumFromThenTo :: Enum a => a -> a -> a -> Bundle v a
+{-# INLINE enumFromThenTo #-}
+enumFromThenTo = M.enumFromThenTo
+
+-- Conversions
+-- -----------
+
+-- | Convert a 'Bundle' to a list
+toList :: Bundle v a -> [a]
+{-# INLINE toList #-}
+-- toList s = unId (M.toList s)
+toList s = build (\c n -> toListFB c n s)
+
+-- This supports foldr/build list fusion that GHC implements
+toListFB :: (a -> b -> b) -> b -> Bundle v a -> b
+{-# INLINE [0] toListFB #-}
+toListFB c n M.Bundle{M.sElems = Stream step t} = go t
+  where
+    go s = case unId (step s) of
+             Yield x s' -> x `c` go s'
+             Skip    s' -> go s'
+             Done       -> n
+
+-- | Create a 'Bundle' from a list
+fromList :: [a] -> Bundle v a
+{-# INLINE fromList #-}
+fromList = M.fromList
+
+-- | Create a 'Bundle' from the first @n@ elements of a list
+--
+-- > fromListN n xs = fromList (take n xs)
+fromListN :: Int -> [a] -> Bundle v a
+{-# INLINE fromListN #-}
+fromListN = M.fromListN
+
+unsafeFromList :: Size -> [a] -> Bundle v a
+{-# INLINE unsafeFromList #-}
+unsafeFromList = M.unsafeFromList
+
+fromVector :: Vector v a => v a -> Bundle v a
+{-# INLINE fromVector #-}
+fromVector = M.fromVector
+
+reVector :: Bundle u a -> Bundle v a
+{-# INLINE reVector #-}
+reVector = M.reVector
+
+fromVectors :: Vector v a => [v a] -> Bundle v a
+{-# INLINE fromVectors #-}
+fromVectors = M.fromVectors
+
+concatVectors :: Vector v a => Bundle u (v a) -> Bundle v a
+{-# INLINE concatVectors #-}
+concatVectors = M.concatVectors
+
+-- | Create a 'Bundle' of values from a 'Bundle' of streamable things
+flatten :: (a -> s) -> (s -> Step s b) -> Size -> Bundle v a -> Bundle v b
+{-# INLINE_FUSED flatten #-}
+flatten mk istep sz = M.flatten (return . mk) (return . istep) sz . lift
+

third_party/bazel/rules_haskell/examples/vector/Data/Vector/Fusion/Bundle/Size.hs

@@ -0,0 +1,121 @@
+-- |
+-- Module      : Data.Vector.Fusion.Bundle.Size
+-- Copyright   : (c) Roman Leshchinskiy 2008-2010
+-- License     : BSD-style
+--
+-- Maintainer  : Roman Leshchinskiy <rl@cse.unsw.edu.au>
+-- Stability   : experimental
+-- Portability : portable
+--
+-- Size hints for streams.
+--
+
+module Data.Vector.Fusion.Bundle.Size (
+  Size(..), clampedSubtract, smaller, larger, toMax, upperBound, lowerBound
+) where
+
+import Data.Vector.Fusion.Util ( delay_inline )
+
+-- | Size hint
+data Size = Exact Int          -- ^ Exact size
+          | Max   Int          -- ^ Upper bound on the size
+          | Unknown            -- ^ Unknown size
+        deriving( Eq, Show )
+
+instance Num Size where
+  Exact m + Exact n = checkedAdd Exact m n
+  Exact m + Max   n = checkedAdd Max m n
+
+  Max   m + Exact n = checkedAdd Max m n
+  Max   m + Max   n = checkedAdd Max m n
+
+  _       + _       = Unknown
+
+
+  Exact m - Exact n = checkedSubtract Exact m n
+  Exact m - Max   _ = Max   m
+
+  Max   m - Exact n = checkedSubtract Max m n
+  Max   m - Max   _ = Max   m
+  Max   m - Unknown = Max   m
+
+  _       - _       = Unknown
+
+
+  fromInteger n     = Exact (fromInteger n)
+
+  (*)    = error "vector: internal error * for Bundle.size isn't defined"
+  abs    = error "vector: internal error abs for Bundle.size isn't defined"
+  signum = error "vector: internal error signum for Bundle.size isn't defined"
+
+{-# INLINE checkedAdd #-}
+checkedAdd :: (Int -> Size) -> Int -> Int -> Size
+checkedAdd con m n
+    -- Note: we assume m and n are >= 0.
+  | r < m || r < n =
+      error $ "Data.Vector.Fusion.Bundle.Size.checkedAdd: overflow: " ++ show r
+  | otherwise = con r
+  where
+    r = m + n
+
+{-# INLINE checkedSubtract #-}
+checkedSubtract :: (Int -> Size) -> Int -> Int -> Size
+checkedSubtract con m n
+  | r < 0 =
+      error $ "Data.Vector.Fusion.Bundle.Size.checkedSubtract: underflow: " ++ show r
+  | otherwise = con r
+  where
+    r = m - n
+
+-- | Subtract two sizes with clamping to 0, for drop-like things
+{-# INLINE clampedSubtract #-}
+clampedSubtract :: Size -> Size -> Size
+clampedSubtract (Exact m) (Exact n) = Exact (max 0 (m - n))
+clampedSubtract (Max   m) (Exact n)
+  | m <= n = Exact 0
+  | otherwise = Max (m - n)
+clampedSubtract (Exact m) (Max   _) = Max m
+clampedSubtract (Max   m) (Max   _) = Max m
+clampedSubtract _         _ = Unknown
+
+-- | Minimum of two size hints
+smaller :: Size -> Size -> Size
+{-# INLINE smaller #-}
+smaller (Exact m) (Exact n) = Exact (delay_inline min m n)
+smaller (Exact m) (Max   n) = Max   (delay_inline min m n)
+smaller (Exact m) Unknown   = Max   m
+smaller (Max   m) (Exact n) = Max   (delay_inline min m n)
+smaller (Max   m) (Max   n) = Max   (delay_inline min m n)
+smaller (Max   m) Unknown   = Max   m
+smaller Unknown   (Exact n) = Max   n
+smaller Unknown   (Max   n) = Max   n
+smaller Unknown   Unknown   = Unknown
+
+-- | Maximum of two size hints
+larger :: Size -> Size -> Size
+{-# INLINE larger #-}
+larger (Exact m) (Exact n)             = Exact (delay_inline max m n)
+larger (Exact m) (Max   n) | m >= n    = Exact m
+                           | otherwise = Max   n
+larger (Max   m) (Exact n) | n >= m    = Exact n
+                           | otherwise = Max   m
+larger (Max   m) (Max   n)             = Max   (delay_inline max m n)
+larger _         _                     = Unknown
+
+-- | Convert a size hint to an upper bound
+toMax :: Size -> Size
+toMax (Exact n) = Max n
+toMax (Max   n) = Max n
+toMax Unknown   = Unknown
+
+-- | Compute the minimum size from a size hint
+lowerBound :: Size -> Int
+lowerBound (Exact n) = n
+lowerBound _         = 0
+
+-- | Compute the maximum size from a size hint if possible
+upperBound :: Size -> Maybe Int
+upperBound (Exact n) = Just n
+upperBound (Max   n) = Just n
+upperBound Unknown   = Nothing
+

third_party/bazel/rules_haskell/examples/vector/Data/Vector/Fusion/Util.hs

@@ -0,0 +1,60 @@
+{-# LANGUAGE CPP #-}
+-- |
+-- Module      : Data.Vector.Fusion.Util
+-- Copyright   : (c) Roman Leshchinskiy 2009
+-- License     : BSD-style
+--
+-- Maintainer  : Roman Leshchinskiy <rl@cse.unsw.edu.au>
+-- Stability   : experimental
+-- Portability : portable
+--
+-- Fusion-related utility types
+--
+
+module Data.Vector.Fusion.Util (
+  Id(..), Box(..),
+
+  delay_inline, delayed_min
+) where
+
+#if !MIN_VERSION_base(4,8,0)
+import Control.Applicative (Applicative(..))
+#endif
+
+-- | Identity monad
+newtype Id a = Id { unId :: a }
+
+instance Functor Id where
+  fmap f (Id x) = Id (f x)
+
+instance Applicative Id where
+  pure = Id
+  Id f <*> Id x = Id (f x)
+
+instance Monad Id where
+  return = pure
+  Id x >>= f = f x
+
+-- | Box monad
+data Box a = Box { unBox :: a }
+
+instance Functor Box where
+  fmap f (Box x) = Box (f x)
+
+instance Applicative Box where
+  pure = Box
+  Box f <*> Box x = Box (f x)
+
+instance Monad Box where
+  return = pure
+  Box x >>= f = f x
+
+-- | Delay inlining a function until late in the game (simplifier phase 0).
+delay_inline :: (a -> b) -> a -> b
+{-# INLINE [0] delay_inline #-}
+delay_inline f = f
+
+-- | `min` inlined in phase 0
+delayed_min :: Int -> Int -> Int
+{-# INLINE [0] delayed_min #-}
+delayed_min m n = min m n

third_party/bazel/rules_haskell/examples/vector/Data/Vector/Generic/Base.hs

@@ -0,0 +1,140 @@
+{-# LANGUAGE Rank2Types, MultiParamTypeClasses, FlexibleContexts,
+             TypeFamilies, ScopedTypeVariables, BangPatterns #-}
+{-# OPTIONS_HADDOCK hide #-}
+
+-- |
+-- Module      : Data.Vector.Generic.Base
+-- Copyright   : (c) Roman Leshchinskiy 2008-2010
+-- License     : BSD-style
+--
+-- Maintainer  : Roman Leshchinskiy <rl@cse.unsw.edu.au>
+-- Stability   : experimental
+-- Portability : non-portable
+--
+-- Class of pure vectors
+--
+
+module Data.Vector.Generic.Base (
+  Vector(..), Mutable
+) where
+
+import           Data.Vector.Generic.Mutable.Base ( MVector )
+import qualified Data.Vector.Generic.Mutable.Base as M
+
+import Control.Monad.Primitive
+
+-- | @Mutable v s a@ is the mutable version of the pure vector type @v a@ with
+-- the state token @s@
+--
+type family Mutable (v :: * -> *) :: * -> * -> *
+
+-- | Class of immutable vectors. Every immutable vector is associated with its
+-- mutable version through the 'Mutable' type family. Methods of this class
+-- should not be used directly. Instead, "Data.Vector.Generic" and other
+-- Data.Vector modules provide safe and fusible wrappers.
+--
+-- Minimum complete implementation:
+--
+--   * 'basicUnsafeFreeze'
+--
+--   * 'basicUnsafeThaw'
+--
+--   * 'basicLength'
+--
+--   * 'basicUnsafeSlice'
+--
+--   * 'basicUnsafeIndexM'
+--
+class MVector (Mutable v) a => Vector v a where
+  -- | /Assumed complexity: O(1)/
+  --
+  -- Unsafely convert a mutable vector to its immutable version
+  -- without copying. The mutable vector may not be used after
+  -- this operation.
+  basicUnsafeFreeze :: PrimMonad m => Mutable v (PrimState m) a -> m (v a)
+
+  -- | /Assumed complexity: O(1)/
+  --
+  -- Unsafely convert an immutable vector to its mutable version without
+  -- copying. The immutable vector may not be used after this operation.
+  basicUnsafeThaw :: PrimMonad m => v a -> m (Mutable v (PrimState m) a)
+
+  -- | /Assumed complexity: O(1)/
+  --
+  -- Yield the length of the vector.
+  basicLength      :: v a -> Int
+
+  -- | /Assumed complexity: O(1)/
+  --
+  -- Yield a slice of the vector without copying it. No range checks are
+  -- performed.
+  basicUnsafeSlice  :: Int -- ^ starting index
+                    -> Int -- ^ length
+                    -> v a -> v a
+
+  -- | /Assumed complexity: O(1)/
+  --
+  -- Yield the element at the given position in a monad. No range checks are
+  -- performed.
+  --
+  -- The monad allows us to be strict in the vector if we want. Suppose we had
+  --
+  -- > unsafeIndex :: v a -> Int -> a
+  --
+  -- instead. Now, if we wanted to copy a vector, we'd do something like
+  --
+  -- > copy mv v ... = ... unsafeWrite mv i (unsafeIndex v i) ...
+  --
+  -- For lazy vectors, the indexing would not be evaluated which means that we
+  -- would retain a reference to the original vector in each element we write.
+  -- This is not what we want!
+  --
+  -- With 'basicUnsafeIndexM', we can do
+  --
+  -- > copy mv v ... = ... case basicUnsafeIndexM v i of
+  -- >                       Box x -> unsafeWrite mv i x ...
+  --
+  -- which does not have this problem because indexing (but not the returned
+  -- element!) is evaluated immediately.
+  --
+  basicUnsafeIndexM  :: Monad m => v a -> Int -> m a
+
+  -- |  /Assumed complexity: O(n)/
+  --
+  -- Copy an immutable vector into a mutable one. The two vectors must have
+  -- the same length but this is not checked.
+  --
+  -- Instances of 'Vector' should redefine this method if they wish to support
+  -- an efficient block copy operation.
+  --
+  -- Default definition: copying basic on 'basicUnsafeIndexM' and
+  -- 'basicUnsafeWrite'.
+  basicUnsafeCopy :: PrimMonad m => Mutable v (PrimState m) a -> v a -> m ()
+
+  {-# INLINE basicUnsafeCopy #-}
+  basicUnsafeCopy !dst !src = do_copy 0
+    where
+      !n = basicLength src
+
+      do_copy i | i < n = do
+                            x <- basicUnsafeIndexM src i
+                            M.basicUnsafeWrite dst i x
+                            do_copy (i+1)
+                | otherwise = return ()
+
+  -- | Evaluate @a@ as far as storing it in a vector would and yield @b@.
+  -- The @v a@ argument only fixes the type and is not touched. The method is
+  -- only used for optimisation purposes. Thus, it is safe for instances of
+  -- 'Vector' to evaluate @a@ less than it would be when stored in a vector
+  -- although this might result in suboptimal code.
+  --
+  -- > elemseq v x y = (singleton x `asTypeOf` v) `seq` y
+  --
+  -- Default defintion: @a@ is not evaluated at all
+  --
+  elemseq :: v a -> a -> b -> b
+
+  {-# INLINE elemseq #-}
+  elemseq _ = \_ x -> x
+
+

third_party/bazel/rules_haskell/examples/vector/Data/Vector/Generic/Mutable/Base.hs

@@ -0,0 +1,145 @@
+{-# LANGUAGE CPP, MultiParamTypeClasses, BangPatterns, TypeFamilies #-}
+-- |
+-- Module      : Data.Vector.Generic.Mutable.Base
+-- Copyright   : (c) Roman Leshchinskiy 2008-2011
+-- License     : BSD-style
+--
+-- Maintainer  : Roman Leshchinskiy <rl@cse.unsw.edu.au>
+-- Stability   : experimental
+-- Portability : non-portable
+--
+-- Class of mutable vectors
+--
+
+module Data.Vector.Generic.Mutable.Base (
+  MVector(..)
+) where
+
+import Control.Monad.Primitive ( PrimMonad, PrimState )
+
+-- Data.Vector.Internal.Check is unused
+#define NOT_VECTOR_MODULE
+#include "vector.h"
+
+-- | Class of mutable vectors parametrised with a primitive state token.
+--
+class MVector v a where
+  -- | Length of the mutable vector. This method should not be
+  -- called directly, use 'length' instead.
+  basicLength       :: v s a -> Int
+
+  -- | Yield a part of the mutable vector without copying it. This method
+  -- should not be called directly, use 'unsafeSlice' instead.
+  basicUnsafeSlice :: Int  -- ^ starting index
+                   -> Int  -- ^ length of the slice
+                   -> v s a
+                   -> v s a
+
+  -- | Check whether two vectors overlap. This method should not be
+  -- called directly, use 'overlaps' instead.
+  basicOverlaps    :: v s a -> v s a -> Bool
+
+  -- | Create a mutable vector of the given length. This method should not be
+  -- called directly, use 'unsafeNew' instead.
+  basicUnsafeNew   :: PrimMonad m => Int -> m (v (PrimState m) a)
+
+  -- | Initialize a vector to a standard value. This is intended to be called as
+  -- part of the safe new operation (and similar operations), to properly blank
+  -- the newly allocated memory if necessary.
+  --
+  -- Vectors that are necessarily initialized as part of creation may implement
+  -- this as a no-op.
+  basicInitialize :: PrimMonad m => v (PrimState m) a -> m ()
+
+  -- | Create a mutable vector of the given length and fill it with an
+  -- initial value. This method should not be called directly, use
+  -- 'replicate' instead.
+  basicUnsafeReplicate :: PrimMonad m => Int -> a -> m (v (PrimState m) a)
+
+  -- | Yield the element at the given position. This method should not be
+  -- called directly, use 'unsafeRead' instead.
+  basicUnsafeRead  :: PrimMonad m => v (PrimState m) a -> Int -> m a
+
+  -- | Replace the element at the given position. This method should not be
+  -- called directly, use 'unsafeWrite' instead.
+  basicUnsafeWrite :: PrimMonad m => v (PrimState m) a -> Int -> a -> m ()
+
+  -- | Reset all elements of the vector to some undefined value, clearing all
+  -- references to external objects. This is usually a noop for unboxed
+  -- vectors. This method should not be called directly, use 'clear' instead.
+  basicClear       :: PrimMonad m => v (PrimState m) a -> m ()
+
+  -- | Set all elements of the vector to the given value. This method should
+  -- not be called directly, use 'set' instead.
+  basicSet         :: PrimMonad m => v (PrimState m) a -> a -> m ()
+
+  -- | Copy a vector. The two vectors may not overlap. This method should not
+  -- be called directly, use 'unsafeCopy' instead.
+  basicUnsafeCopy  :: PrimMonad m => v (PrimState m) a   -- ^ target
+                                  -> v (PrimState m) a   -- ^ source
+                                  -> m ()
+
+  -- | Move the contents of a vector. The two vectors may overlap. This method
+  -- should not be called directly, use 'unsafeMove' instead.
+  basicUnsafeMove  :: PrimMonad m => v (PrimState m) a   -- ^ target
+                                  -> v (PrimState m) a   -- ^ source
+                                  -> m ()
+
+  -- | Grow a vector by the given number of elements. This method should not be
+  -- called directly, use 'unsafeGrow' instead.
+  basicUnsafeGrow  :: PrimMonad m => v (PrimState m) a -> Int
+                                                       -> m (v (PrimState m) a)
+
+  {-# INLINE basicUnsafeReplicate #-}
+  basicUnsafeReplicate n x
+    = do
+        v <- basicUnsafeNew n
+        basicSet v x
+        return v
+
+  {-# INLINE basicClear #-}
+  basicClear _ = return ()
+
+  {-# INLINE basicSet #-}
+  basicSet !v x
+    | n == 0    = return ()
+    | otherwise = do
+                    basicUnsafeWrite v 0 x
+                    do_set 1
+    where
+      !n = basicLength v
+
+      do_set i | 2*i < n = do basicUnsafeCopy (basicUnsafeSlice i i v)
+                                              (basicUnsafeSlice 0 i v)
+                              do_set (2*i)
+               | otherwise = basicUnsafeCopy (basicUnsafeSlice i (n-i) v)
+                                             (basicUnsafeSlice 0 (n-i) v)
+
+  {-# INLINE basicUnsafeCopy #-}
+  basicUnsafeCopy !dst !src = do_copy 0
+    where
+      !n = basicLength src
+
+      do_copy i | i < n = do
+                            x <- basicUnsafeRead src i
+                            basicUnsafeWrite dst i x
+                            do_copy (i+1)
+                | otherwise = return ()
+
+  {-# INLINE basicUnsafeMove #-}
+  basicUnsafeMove !dst !src
+    | basicOverlaps dst src = do
+        srcCopy <- basicUnsafeNew (basicLength src)
+        basicUnsafeCopy srcCopy src
+        basicUnsafeCopy dst srcCopy
+    | otherwise = basicUnsafeCopy dst src
+
+  {-# INLINE basicUnsafeGrow #-}
+  basicUnsafeGrow v by
+    = do
+        v' <- basicUnsafeNew (n+by)
+        basicUnsafeCopy (basicUnsafeSlice 0 n v') v
+        return v'
+    where
+      n = basicLength v
+

third_party/bazel/rules_haskell/examples/vector/Data/Vector/Generic/New.hs

@@ -0,0 +1,178 @@
+{-# LANGUAGE CPP, Rank2Types, FlexibleContexts, MultiParamTypeClasses #-}
+
+-- |
+-- Module      : Data.Vector.Generic.New
+-- Copyright   : (c) Roman Leshchinskiy 2008-2010
+-- License     : BSD-style
+--
+-- Maintainer  : Roman Leshchinskiy <rl@cse.unsw.edu.au>
+-- Stability   : experimental
+-- Portability : non-portable
+--
+-- Purely functional interface to initialisation of mutable vectors
+--
+
+module Data.Vector.Generic.New (
+  New(..), create, run, runPrim, apply, modify, modifyWithBundle,
+  unstream, transform, unstreamR, transformR,
+  slice, init, tail, take, drop,
+  unsafeSlice, unsafeInit, unsafeTail
+) where
+
+import qualified Data.Vector.Generic.Mutable as MVector
+
+import           Data.Vector.Generic.Base ( Vector, Mutable )
+
+import           Data.Vector.Fusion.Bundle ( Bundle )
+import qualified Data.Vector.Fusion.Bundle as Bundle
+import           Data.Vector.Fusion.Stream.Monadic ( Stream )
+import           Data.Vector.Fusion.Bundle.Size
+
+import Control.Monad.Primitive
+import Control.Monad.ST ( ST )
+import Control.Monad  ( liftM )
+import Prelude hiding ( init, tail, take, drop, reverse, map, filter )
+
+-- Data.Vector.Internal.Check is unused
+#define NOT_VECTOR_MODULE
+#include "vector.h"
+
+data New v a = New (forall s. ST s (Mutable v s a))
+
+create :: (forall s. ST s (Mutable v s a)) -> New v a
+{-# INLINE create #-}
+create p = New p
+
+run :: New v a -> ST s (Mutable v s a)
+{-# INLINE run #-}
+run (New p) = p
+
+runPrim :: PrimMonad m => New v a -> m (Mutable v (PrimState m) a)
+{-# INLINE runPrim #-}
+runPrim (New p) = primToPrim p
+
+apply :: (forall s. Mutable v s a -> Mutable v s a) -> New v a -> New v a
+{-# INLINE apply #-}
+apply f (New p) = New (liftM f p)
+
+modify :: (forall s. Mutable v s a -> ST s ()) -> New v a -> New v a
+{-# INLINE modify #-}
+modify f (New p) = New (do { v <- p; f v; return v })
+
+modifyWithBundle :: (forall s. Mutable v s a -> Bundle u b -> ST s ())
+                 -> New v a -> Bundle u b -> New v a
+{-# INLINE_FUSED modifyWithBundle #-}
+modifyWithBundle f (New p) s = s `seq` New (do { v <- p; f v s; return v })
+
+unstream :: Vector v a => Bundle v a -> New v a
+{-# INLINE_FUSED unstream #-}
+unstream s = s `seq` New (MVector.vunstream s)
+
+transform
+  :: Vector v a => (forall m. Monad m => Stream m a -> Stream m a)
+                -> (Size -> Size) -> New v a -> New v a
+{-# INLINE_FUSED transform #-}
+transform f _ (New p) = New (MVector.transform f =<< p)
+
+{-# RULES
+
+"transform/transform [New]"
+  forall (f1 :: forall m. Monad m => Stream m a -> Stream m a)
+         (f2 :: forall m. Monad m => Stream m a -> Stream m a)
+         g1 g2 p .
+  transform f1 g1 (transform f2 g2 p) = transform (f1 . f2) (g1 . g2) p
+
+"transform/unstream [New]"
+  forall (f :: forall m. Monad m => Stream m a -> Stream m a)
+         g s.
+  transform f g (unstream s) = unstream (Bundle.inplace f g s)  #-}
+
+
+
+
+unstreamR :: Vector v a => Bundle v a -> New v a
+{-# INLINE_FUSED unstreamR #-}
+unstreamR s = s `seq` New (MVector.unstreamR s)
+
+transformR
+  :: Vector v a => (forall m. Monad m => Stream m a -> Stream m a)
+                -> (Size -> Size) -> New v a -> New v a
+{-# INLINE_FUSED transformR #-}
+transformR f _ (New p) = New (MVector.transformR f =<< p)
+
+{-# RULES
+
+"transformR/transformR [New]"
+  forall (f1 :: forall m. Monad m => Stream m a -> Stream m a)
+         (f2 :: forall m. Monad m => Stream m a -> Stream m a)
+         g1 g2
+         p .
+  transformR f1 g1 (transformR f2 g2 p) = transformR (f1 . f2) (g1 . g2) p
+
+"transformR/unstreamR [New]"
+  forall (f :: forall m. Monad m => Stream m a -> Stream m a)
+         g s.
+  transformR f g (unstreamR s) = unstreamR (Bundle.inplace f g s)  #-}
+
+
+
+slice :: Vector v a => Int -> Int -> New v a -> New v a
+{-# INLINE_FUSED slice #-}
+slice i n m = apply (MVector.slice i n) m
+
+init :: Vector v a => New v a -> New v a
+{-# INLINE_FUSED init #-}
+init m = apply MVector.init m
+
+tail :: Vector v a => New v a -> New v a
+{-# INLINE_FUSED tail #-}
+tail m = apply MVector.tail m
+
+take :: Vector v a => Int -> New v a -> New v a
+{-# INLINE_FUSED take #-}
+take n m = apply (MVector.take n) m
+
+drop :: Vector v a => Int -> New v a -> New v a
+{-# INLINE_FUSED drop #-}
+drop n m = apply (MVector.drop n) m
+
+unsafeSlice :: Vector v a => Int -> Int -> New v a -> New v a
+{-# INLINE_FUSED unsafeSlice #-}
+unsafeSlice i n m = apply (MVector.unsafeSlice i n) m
+
+unsafeInit :: Vector v a => New v a -> New v a
+{-# INLINE_FUSED unsafeInit #-}
+unsafeInit m = apply MVector.unsafeInit m
+
+unsafeTail :: Vector v a => New v a -> New v a
+{-# INLINE_FUSED unsafeTail #-}
+unsafeTail m = apply MVector.unsafeTail m
+
+{-# RULES
+
+"slice/unstream [New]" forall i n s.
+  slice i n (unstream s) = unstream (Bundle.slice i n s)
+
+"init/unstream [New]" forall s.
+  init (unstream s) = unstream (Bundle.init s)
+
+"tail/unstream [New]" forall s.
+  tail (unstream s) = unstream (Bundle.tail s)
+
+"take/unstream [New]" forall n s.
+  take n (unstream s) = unstream (Bundle.take n s)
+
+"drop/unstream [New]" forall n s.
+  drop n (unstream s) = unstream (Bundle.drop n s)
+
+"unsafeSlice/unstream [New]" forall i n s.
+  unsafeSlice i n (unstream s) = unstream (Bundle.slice i n s)
+
+"unsafeInit/unstream [New]" forall s.
+  unsafeInit (unstream s) = unstream (Bundle.init s)
+
+"unsafeTail/unstream [New]" forall s.
+  unsafeTail (unstream s) = unstream (Bundle.tail s)   #-}
+
+
+

third_party/bazel/rules_haskell/examples/vector/Data/Vector/Internal/Check.hs

@@ -0,0 +1,152 @@
+{-# LANGUAGE CPP #-}
+
+-- |
+-- Module      : Data.Vector.Internal.Check
+-- Copyright   : (c) Roman Leshchinskiy 2009
+-- License     : BSD-style
+--
+-- Maintainer  : Roman Leshchinskiy <rl@cse.unsw.edu.au>
+-- Stability   : experimental
+-- Portability : non-portable
+--
+-- Bounds checking infrastructure
+--
+
+{-# LANGUAGE MagicHash #-}
+
+module Data.Vector.Internal.Check (
+  Checks(..), doChecks,
+
+  error, internalError,
+  check, checkIndex, checkLength, checkSlice
+) where
+
+import GHC.Base( Int(..) )
+import GHC.Prim( Int# )
+import Prelude hiding( error, (&&), (||), not )
+import qualified Prelude as P
+
+-- NOTE: This is a workaround for GHC's weird behaviour where it doesn't inline
+-- these functions into unfoldings which makes the intermediate code size
+-- explode. See http://hackage.haskell.org/trac/ghc/ticket/5539.
+infixr 2 ||
+infixr 3 &&
+
+not :: Bool -> Bool
+{-# INLINE not #-}
+not True = False
+not False = True
+
+(&&) :: Bool -> Bool -> Bool
+{-# INLINE (&&) #-}
+False && _ = False
+True && x = x
+
+(||) :: Bool -> Bool -> Bool
+{-# INLINE (||) #-}
+True || _ = True
+False || x = x
+
+
+data Checks = Bounds | Unsafe | Internal deriving( Eq )
+
+doBoundsChecks :: Bool
+#ifdef VECTOR_BOUNDS_CHECKS
+doBoundsChecks = True
+#else
+doBoundsChecks = False
+#endif
+
+doUnsafeChecks :: Bool
+#ifdef VECTOR_UNSAFE_CHECKS
+doUnsafeChecks = True
+#else
+doUnsafeChecks = False
+#endif
+
+doInternalChecks :: Bool
+#ifdef VECTOR_INTERNAL_CHECKS
+doInternalChecks = True
+#else
+doInternalChecks = False
+#endif
+
+
+doChecks :: Checks -> Bool
+{-# INLINE doChecks #-}
+doChecks Bounds   = doBoundsChecks
+doChecks Unsafe   = doUnsafeChecks
+doChecks Internal = doInternalChecks
+
+error_msg :: String -> Int -> String -> String -> String
+error_msg file line loc msg = file ++ ":" ++ show line ++ " (" ++ loc ++ "): " ++ msg
+
+error :: String -> Int -> String -> String -> a
+{-# NOINLINE error #-}
+error file line loc msg
+  = P.error $ error_msg file line loc msg
+
+internalError :: String -> Int -> String -> String -> a
+{-# NOINLINE internalError #-}
+internalError file line loc msg
+  = P.error $ unlines
+        ["*** Internal error in package vector ***"
+        ,"*** Please submit a bug report at http://trac.haskell.org/vector"
+        ,error_msg file line loc msg]
+
+
+checkError :: String -> Int -> Checks -> String -> String -> a
+{-# NOINLINE checkError #-}
+checkError file line kind loc msg
+  = case kind of
+      Internal -> internalError file line loc msg
+      _ -> error file line loc msg
+
+check :: String -> Int -> Checks -> String -> String -> Bool -> a -> a
+{-# INLINE check #-}
+check file line kind loc msg cond x
+  | not (doChecks kind) || cond = x
+  | otherwise = checkError file line kind loc msg
+
+checkIndex_msg :: Int -> Int -> String
+{-# INLINE checkIndex_msg #-}
+checkIndex_msg (I# i#) (I# n#) = checkIndex_msg# i# n#
+
+checkIndex_msg# :: Int# -> Int# -> String
+{-# NOINLINE checkIndex_msg# #-}
+checkIndex_msg# i# n# = "index out of bounds " ++ show (I# i#, I# n#)
+
+checkIndex :: String -> Int -> Checks -> String -> Int -> Int -> a -> a
+{-# INLINE checkIndex #-}
+checkIndex file line kind loc i n x
+  = check file line kind loc (checkIndex_msg i n) (i >= 0 && i<n) x
+
+
+checkLength_msg :: Int -> String
+{-# INLINE checkLength_msg #-}
+checkLength_msg (I# n#) = checkLength_msg# n#
+
+checkLength_msg# :: Int# -> String
+{-# NOINLINE checkLength_msg# #-}
+checkLength_msg# n# = "negative length " ++ show (I# n#)
+
+checkLength :: String -> Int -> Checks -> String -> Int -> a -> a
+{-# INLINE checkLength #-}
+checkLength file line kind loc n x
+  = check file line kind loc (checkLength_msg n) (n >= 0) x
+
+
+checkSlice_msg :: Int -> Int -> Int -> String
+{-# INLINE checkSlice_msg #-}
+checkSlice_msg (I# i#) (I# m#) (I# n#) = checkSlice_msg# i# m# n#
+
+checkSlice_msg# :: Int# -> Int# -> Int# -> String
+{-# NOINLINE checkSlice_msg# #-}
+checkSlice_msg# i# m# n# = "invalid slice " ++ show (I# i#, I# m#, I# n#)
+
+checkSlice :: String -> Int -> Checks -> String -> Int -> Int -> Int -> a -> a
+{-# INLINE checkSlice #-}
+checkSlice file line kind loc i m n x
+  = check file line kind loc (checkSlice_msg i m n)
+                             (i >= 0 && m >= 0 && i+m <= n) x
+

third_party/bazel/rules_haskell/examples/vector/Data/Vector/Mutable.hs

@@ -0,0 +1,416 @@
+{-# LANGUAGE CPP, DeriveDataTypeable, MultiParamTypeClasses, FlexibleInstances, BangPatterns, TypeFamilies #-}
+
+-- |
+-- Module      : Data.Vector.Mutable
+-- Copyright   : (c) Roman Leshchinskiy 2008-2010
+-- License     : BSD-style
+--
+-- Maintainer  : Roman Leshchinskiy <rl@cse.unsw.edu.au>
+-- Stability   : experimental
+-- Portability : non-portable
+--
+-- Mutable boxed vectors.
+--
+
+module Data.Vector.Mutable (
+  -- * Mutable boxed vectors
+  MVector(..), IOVector, STVector,
+
+  -- * Accessors
+
+  -- ** Length information
+  length, null,
+
+  -- ** Extracting subvectors
+  slice, init, tail, take, drop, splitAt,
+  unsafeSlice, unsafeInit, unsafeTail, unsafeTake, unsafeDrop,
+
+  -- ** Overlapping
+  overlaps,
+
+  -- * Construction
+
+  -- ** Initialisation
+  new, unsafeNew, replicate, replicateM, clone,
+
+  -- ** Growing
+  grow, unsafeGrow,
+
+  -- ** Restricting memory usage
+  clear,
+
+  -- * Accessing individual elements
+  read, write, modify, swap,
+  unsafeRead, unsafeWrite, unsafeModify, unsafeSwap,
+
+  -- * Modifying vectors
+  nextPermutation,
+
+  -- ** Filling and copying
+  set, copy, move, unsafeCopy, unsafeMove
+) where
+
+import           Control.Monad (when)
+import qualified Data.Vector.Generic.Mutable as G
+import           Data.Primitive.Array
+import           Control.Monad.Primitive
+
+import Prelude hiding ( length, null, replicate, reverse, read,
+                        take, drop, splitAt, init, tail )
+
+import Data.Typeable ( Typeable )
+
+#include "vector.h"
+
+-- | Mutable boxed vectors keyed on the monad they live in ('IO' or @'ST' s@).
+data MVector s a = MVector {-# UNPACK #-} !Int
+                           {-# UNPACK #-} !Int
+                           {-# UNPACK #-} !(MutableArray s a)
+        deriving ( Typeable )
+
+type IOVector = MVector RealWorld
+type STVector s = MVector s
+
+-- NOTE: This seems unsafe, see http://trac.haskell.org/vector/ticket/54
+{-
+instance NFData a => NFData (MVector s a) where
+    rnf (MVector i n arr) = unsafeInlineST $ force i
+        where
+          force !ix | ix < n    = do x <- readArray arr ix
+                                     rnf x `seq` force (ix+1)
+                    | otherwise = return ()
+-}
+
+instance G.MVector MVector a where
+  {-# INLINE basicLength #-}
+  basicLength (MVector _ n _) = n
+
+  {-# INLINE basicUnsafeSlice #-}
+  basicUnsafeSlice j m (MVector i _ arr) = MVector (i+j) m arr
+
+  {-# INLINE basicOverlaps #-}
+  basicOverlaps (MVector i m arr1) (MVector j n arr2)
+    = sameMutableArray arr1 arr2
+      && (between i j (j+n) || between j i (i+m))
+    where
+      between x y z = x >= y && x < z
+
+  {-# INLINE basicUnsafeNew #-}
+  basicUnsafeNew n
+    = do
+        arr <- newArray n uninitialised
+        return (MVector 0 n arr)
+
+  {-# INLINE basicInitialize #-}
+  -- initialization is unnecessary for boxed vectors
+  basicInitialize _ = return ()
+
+  {-# INLINE basicUnsafeReplicate #-}
+  basicUnsafeReplicate n x
+    = do
+        arr <- newArray n x
+        return (MVector 0 n arr)
+
+  {-# INLINE basicUnsafeRead #-}
+  basicUnsafeRead (MVector i _ arr) j = readArray arr (i+j)
+
+  {-# INLINE basicUnsafeWrite #-}
+  basicUnsafeWrite (MVector i _ arr) j x = writeArray arr (i+j) x
+
+  {-# INLINE basicUnsafeCopy #-}
+  basicUnsafeCopy (MVector i n dst) (MVector j _ src)
+    = copyMutableArray dst i src j n
+
+  basicUnsafeMove dst@(MVector iDst n arrDst) src@(MVector iSrc _ arrSrc)
+    = case n of
+        0 -> return ()
+        1 -> readArray arrSrc iSrc >>= writeArray arrDst iDst
+        2 -> do
+               x <- readArray arrSrc iSrc
+               y <- readArray arrSrc (iSrc + 1)
+               writeArray arrDst iDst x
+               writeArray arrDst (iDst + 1) y
+        _
+          | overlaps dst src
+             -> case compare iDst iSrc of
+                  LT -> moveBackwards arrDst iDst iSrc n
+                  EQ -> return ()
+                  GT | (iDst - iSrc) * 2 < n
+                        -> moveForwardsLargeOverlap arrDst iDst iSrc n
+                     | otherwise
+                        -> moveForwardsSmallOverlap arrDst iDst iSrc n
+          | otherwise -> G.basicUnsafeCopy dst src
+
+  {-# INLINE basicClear #-}
+  basicClear v = G.set v uninitialised
+
+{-# INLINE moveBackwards #-}
+moveBackwards :: PrimMonad m => MutableArray (PrimState m) a -> Int -> Int -> Int -> m ()
+moveBackwards !arr !dstOff !srcOff !len =
+  INTERNAL_CHECK(check) "moveBackwards" "not a backwards move" (dstOff < srcOff)
+  $ loopM len $ \ i -> readArray arr (srcOff + i) >>= writeArray arr (dstOff + i)
+
+{-# INLINE moveForwardsSmallOverlap #-}
+-- Performs a move when dstOff > srcOff, optimized for when the overlap of the intervals is small.
+moveForwardsSmallOverlap :: PrimMonad m => MutableArray (PrimState m) a -> Int -> Int -> Int -> m ()
+moveForwardsSmallOverlap !arr !dstOff !srcOff !len =
+  INTERNAL_CHECK(check) "moveForwardsSmallOverlap" "not a forward move" (dstOff > srcOff)
+  $ do
+      tmp <- newArray overlap uninitialised
+      loopM overlap $ \ i -> readArray arr (dstOff + i) >>= writeArray tmp i
+      loopM nonOverlap $ \ i -> readArray arr (srcOff + i) >>= writeArray arr (dstOff + i)
+      loopM overlap $ \ i -> readArray tmp i >>= writeArray arr (dstOff + nonOverlap + i)
+  where nonOverlap = dstOff - srcOff; overlap = len - nonOverlap
+
+-- Performs a move when dstOff > srcOff, optimized for when the overlap of the intervals is large.
+moveForwardsLargeOverlap :: PrimMonad m => MutableArray (PrimState m) a -> Int -> Int -> Int -> m ()
+moveForwardsLargeOverlap !arr !dstOff !srcOff !len =
+  INTERNAL_CHECK(check) "moveForwardsLargeOverlap" "not a forward move" (dstOff > srcOff)
+  $ do
+      queue <- newArray nonOverlap uninitialised
+      loopM nonOverlap $ \ i -> readArray arr (srcOff + i) >>= writeArray queue i
+      let mov !i !qTop = when (i < dstOff + len) $ do
+            x <- readArray arr i
+            y <- readArray queue qTop
+            writeArray arr i y
+            writeArray queue qTop x
+            mov (i+1) (if qTop + 1 >= nonOverlap then 0 else qTop + 1)
+      mov dstOff 0
+  where nonOverlap = dstOff - srcOff
+
+{-# INLINE loopM #-}
+loopM :: Monad m => Int -> (Int -> m a) -> m ()
+loopM !n k = let
+  go i = when (i < n) (k i >> go (i+1))
+  in go 0
+
+uninitialised :: a
+uninitialised = error "Data.Vector.Mutable: uninitialised element"
+
+-- Length information
+-- ------------------
+
+-- | Length of the mutable vector.
+length :: MVector s a -> Int
+{-# INLINE length #-}
+length = G.length
+
+-- | Check whether the vector is empty
+null :: MVector s a -> Bool
+{-# INLINE null #-}
+null = G.null
+
+-- Extracting subvectors
+-- ---------------------
+
+-- | Yield a part of the mutable vector without copying it.
+slice :: Int -> Int -> MVector s a -> MVector s a
+{-# INLINE slice #-}
+slice = G.slice
+
+take :: Int -> MVector s a -> MVector s a
+{-# INLINE take #-}
+take = G.take
+
+drop :: Int -> MVector s a -> MVector s a
+{-# INLINE drop #-}
+drop = G.drop
+
+{-# INLINE splitAt #-}
+splitAt :: Int -> MVector s a -> (MVector s a, MVector s a)
+splitAt = G.splitAt
+
+init :: MVector s a -> MVector s a
+{-# INLINE init #-}
+init = G.init
+
+tail :: MVector s a -> MVector s a
+{-# INLINE tail #-}
+tail = G.tail
+
+-- | Yield a part of the mutable vector without copying it. No bounds checks
+-- are performed.
+unsafeSlice :: Int  -- ^ starting index
+            -> Int  -- ^ length of the slice
+            -> MVector s a
+            -> MVector s a
+{-# INLINE unsafeSlice #-}
+unsafeSlice = G.unsafeSlice
+
+unsafeTake :: Int -> MVector s a -> MVector s a
+{-# INLINE unsafeTake #-}
+unsafeTake = G.unsafeTake
+
+unsafeDrop :: Int -> MVector s a -> MVector s a
+{-# INLINE unsafeDrop #-}
+unsafeDrop = G.unsafeDrop
+
+unsafeInit :: MVector s a -> MVector s a
+{-# INLINE unsafeInit #-}
+unsafeInit = G.unsafeInit
+
+unsafeTail :: MVector s a -> MVector s a
+{-# INLINE unsafeTail #-}
+unsafeTail = G.unsafeTail
+
+-- Overlapping
+-- -----------
+
+-- | Check whether two vectors overlap.
+overlaps :: MVector s a -> MVector s a -> Bool
+{-# INLINE overlaps #-}
+overlaps = G.overlaps
+
+-- Initialisation
+-- --------------
+
+-- | Create a mutable vector of the given length.
+new :: PrimMonad m => Int -> m (MVector (PrimState m) a)
+{-# INLINE new #-}
+new = G.new
+
+-- | Create a mutable vector of the given length. The memory is not initialized.
+unsafeNew :: PrimMonad m => Int -> m (MVector (PrimState m) a)
+{-# INLINE unsafeNew #-}
+unsafeNew = G.unsafeNew
+
+-- | Create a mutable vector of the given length (0 if the length is negative)
+-- and fill it with an initial value.
+replicate :: PrimMonad m => Int -> a -> m (MVector (PrimState m) a)
+{-# INLINE replicate #-}
+replicate = G.replicate
+
+-- | Create a mutable vector of the given length (0 if the length is negative)
+-- and fill it with values produced by repeatedly executing the monadic action.
+replicateM :: PrimMonad m => Int -> m a -> m (MVector (PrimState m) a)
+{-# INLINE replicateM #-}
+replicateM = G.replicateM
+
+-- | Create a copy of a mutable vector.
+clone :: PrimMonad m => MVector (PrimState m) a -> m (MVector (PrimState m) a)
+{-# INLINE clone #-}
+clone = G.clone
+
+-- Growing
+-- -------
+
+-- | Grow a vector by the given number of elements. The number must be
+-- positive.
+grow :: PrimMonad m
+              => MVector (PrimState m) a -> Int -> m (MVector (PrimState m) a)
+{-# INLINE grow #-}
+grow = G.grow
+
+-- | Grow a vector by the given number of elements. The number must be
+-- positive but this is not checked.
+unsafeGrow :: PrimMonad m
+               => MVector (PrimState m) a -> Int -> m (MVector (PrimState m) a)
+{-# INLINE unsafeGrow #-}
+unsafeGrow = G.unsafeGrow
+
+-- Restricting memory usage
+-- ------------------------
+
+-- | Reset all elements of the vector to some undefined value, clearing all
+-- references to external objects. This is usually a noop for unboxed vectors.
+clear :: PrimMonad m => MVector (PrimState m) a -> m ()
+{-# INLINE clear #-}
+clear = G.clear
+
+-- Accessing individual elements
+-- -----------------------------
+
+-- | Yield the element at the given position.
+read :: PrimMonad m => MVector (PrimState m) a -> Int -> m a
+{-# INLINE read #-}
+read = G.read
+
+-- | Replace the element at the given position.
+write :: PrimMonad m => MVector (PrimState m) a -> Int -> a -> m ()
+{-# INLINE write #-}
+write = G.write
+
+-- | Modify the element at the given position.
+modify :: PrimMonad m => MVector (PrimState m) a -> (a -> a) -> Int -> m ()
+{-# INLINE modify #-}
+modify = G.modify
+
+-- | Swap the elements at the given positions.
+swap :: PrimMonad m => MVector (PrimState m) a -> Int -> Int -> m ()
+{-# INLINE swap #-}
+swap = G.swap
+
+
+-- | Yield the element at the given position. No bounds checks are performed.
+unsafeRead :: PrimMonad m => MVector (PrimState m) a -> Int -> m a
+{-# INLINE unsafeRead #-}
+unsafeRead = G.unsafeRead
+
+-- | Replace the element at the given position. No bounds checks are performed.
+unsafeWrite :: PrimMonad m => MVector (PrimState m) a -> Int -> a -> m ()
+{-# INLINE unsafeWrite #-}
+unsafeWrite = G.unsafeWrite
+
+-- | Modify the element at the given position. No bounds checks are performed.
+unsafeModify :: PrimMonad m => MVector (PrimState m) a -> (a -> a) -> Int -> m ()
+{-# INLINE unsafeModify #-}
+unsafeModify = G.unsafeModify
+
+-- | Swap the elements at the given positions. No bounds checks are performed.
+unsafeSwap :: PrimMonad m => MVector (PrimState m) a -> Int -> Int -> m ()
+{-# INLINE unsafeSwap #-}
+unsafeSwap = G.unsafeSwap
+
+-- Filling and copying
+-- -------------------
+
+-- | Set all elements of the vector to the given value.
+set :: PrimMonad m => MVector (PrimState m) a -> a -> m ()
+{-# INLINE set #-}
+set = G.set
+
+-- | Copy a vector. The two vectors must have the same length and may not
+-- overlap.
+copy :: PrimMonad m
+                 => MVector (PrimState m) a -> MVector (PrimState m) a -> m ()
+{-# INLINE copy #-}
+copy = G.copy
+
+-- | Copy a vector. The two vectors must have the same length and may not
+-- overlap. This is not checked.
+unsafeCopy :: PrimMonad m => MVector (PrimState m) a   -- ^ target
+                          -> MVector (PrimState m) a   -- ^ source
+                          -> m ()
+{-# INLINE unsafeCopy #-}
+unsafeCopy = G.unsafeCopy
+
+-- | Move the contents of a vector. The two vectors must have the same
+-- length.
+--
+-- If the vectors do not overlap, then this is equivalent to 'copy'.
+-- Otherwise, the copying is performed as if the source vector were
+-- copied to a temporary vector and then the temporary vector was copied
+-- to the target vector.
+move :: PrimMonad m
+                 => MVector (PrimState m) a -> MVector (PrimState m) a -> m ()
+{-# INLINE move #-}
+move = G.move
+
+-- | Move the contents of a vector. The two vectors must have the same
+-- length, but this is not checked.
+--
+-- If the vectors do not overlap, then this is equivalent to 'unsafeCopy'.
+-- Otherwise, the copying is performed as if the source vector were
+-- copied to a temporary vector and then the temporary vector was copied
+-- to the target vector.
+unsafeMove :: PrimMonad m => MVector (PrimState m) a   -- ^ target
+                          -> MVector (PrimState m) a   -- ^ source
+                          -> m ()
+{-# INLINE unsafeMove #-}
+unsafeMove = G.unsafeMove
+
+-- | Compute the next (lexicographically) permutation of given vector in-place.
+--   Returns False when input is the last permtuation
+nextPermutation :: (PrimMonad m,Ord e) => MVector (PrimState m) e -> m Bool
+{-# INLINE nextPermutation #-}
+nextPermutation = G.nextPermutation

third_party/bazel/rules_haskell/examples/vector/Data/Vector/Primitive/Mutable.hs

@@ -0,0 +1,366 @@
+{-# LANGUAGE CPP, DeriveDataTypeable, MultiParamTypeClasses, FlexibleInstances, ScopedTypeVariables #-}
+
+-- |
+-- Module      : Data.Vector.Primitive.Mutable
+-- Copyright   : (c) Roman Leshchinskiy 2008-2010
+-- License     : BSD-style
+--
+-- Maintainer  : Roman Leshchinskiy <rl@cse.unsw.edu.au>
+-- Stability   : experimental
+-- Portability : non-portable
+--
+-- Mutable primitive vectors.
+--
+
+module Data.Vector.Primitive.Mutable (
+  -- * Mutable vectors of primitive types
+  MVector(..), IOVector, STVector, Prim,
+
+  -- * Accessors
+
+  -- ** Length information
+  length, null,
+
+  -- ** Extracting subvectors
+  slice, init, tail, take, drop, splitAt,
+  unsafeSlice, unsafeInit, unsafeTail, unsafeTake, unsafeDrop,
+
+  -- ** Overlapping
+  overlaps,
+
+  -- * Construction
+
+  -- ** Initialisation
+  new, unsafeNew, replicate, replicateM, clone,
+
+  -- ** Growing
+  grow, unsafeGrow,
+
+  -- ** Restricting memory usage
+  clear,
+
+  -- * Accessing individual elements
+  read, write, modify, swap,
+  unsafeRead, unsafeWrite, unsafeModify, unsafeSwap,
+
+  -- * Modifying vectors
+  nextPermutation,
+
+  -- ** Filling and copying
+  set, copy, move, unsafeCopy, unsafeMove
+) where
+
+import qualified Data.Vector.Generic.Mutable as G
+import           Data.Primitive.ByteArray
+import           Data.Primitive ( Prim, sizeOf )
+import           Data.Word ( Word8 )
+import           Control.Monad.Primitive
+import           Control.Monad ( liftM )
+
+import Control.DeepSeq ( NFData(rnf) )
+
+import Prelude hiding ( length, null, replicate, reverse, map, read,
+                        take, drop, splitAt, init, tail )
+
+import Data.Typeable ( Typeable )
+
+-- Data.Vector.Internal.Check is unnecessary
+#define NOT_VECTOR_MODULE
+#include "vector.h"
+
+-- | Mutable vectors of primitive types.
+data MVector s a = MVector {-# UNPACK #-} !Int
+                           {-# UNPACK #-} !Int
+                           {-# UNPACK #-} !(MutableByteArray s) -- ^ offset, length, underlying mutable byte array
+        deriving ( Typeable )
+
+type IOVector = MVector RealWorld
+type STVector s = MVector s
+
+instance NFData (MVector s a) where
+  rnf (MVector _ _ _) = ()
+
+instance Prim a => G.MVector MVector a where
+  basicLength (MVector _ n _) = n
+  basicUnsafeSlice j m (MVector i _ arr)
+    = MVector (i+j) m arr
+
+  {-# INLINE basicOverlaps #-}
+  basicOverlaps (MVector i m arr1) (MVector j n arr2)
+    = sameMutableByteArray arr1 arr2
+      && (between i j (j+n) || between j i (i+m))
+    where
+      between x y z = x >= y && x < z
+
+  {-# INLINE basicUnsafeNew #-}
+  basicUnsafeNew n
+    | n < 0 = error $ "Primitive.basicUnsafeNew: negative length: " ++ show n
+    | n > mx = error $ "Primitive.basicUnsafeNew: length to large: " ++ show n
+    | otherwise = MVector 0 n `liftM` newByteArray (n * size)
+    where
+      size = sizeOf (undefined :: a)
+      mx = maxBound `div` size :: Int
+
+  {-# INLINE basicInitialize #-}
+  basicInitialize (MVector off n v) =
+      setByteArray v (off * size) (n * size) (0 :: Word8)
+    where
+      size = sizeOf (undefined :: a)
+
+
+  {-# INLINE basicUnsafeRead #-}
+  basicUnsafeRead (MVector i _ arr) j = readByteArray arr (i+j)
+
+  {-# INLINE basicUnsafeWrite #-}
+  basicUnsafeWrite (MVector i _ arr) j x = writeByteArray arr (i+j) x
+
+  {-# INLINE basicUnsafeCopy #-}
+  basicUnsafeCopy (MVector i n dst) (MVector j _ src)
+    = copyMutableByteArray dst (i*sz) src (j*sz) (n*sz)
+    where
+      sz = sizeOf (undefined :: a)
+
+  {-# INLINE basicUnsafeMove #-}
+  basicUnsafeMove (MVector i n dst) (MVector j _ src)
+    = moveByteArray dst (i*sz) src (j*sz) (n * sz)
+    where
+      sz = sizeOf (undefined :: a)
+
+  {-# INLINE basicSet #-}
+  basicSet (MVector i n arr) x = setByteArray arr i n x
+
+-- Length information
+-- ------------------
+
+-- | Length of the mutable vector.
+length :: Prim a => MVector s a -> Int
+{-# INLINE length #-}
+length = G.length
+
+-- | Check whether the vector is empty
+null :: Prim a => MVector s a -> Bool
+{-# INLINE null #-}
+null = G.null
+
+-- Extracting subvectors
+-- ---------------------
+
+-- | Yield a part of the mutable vector without copying it.
+slice :: Prim a => Int -> Int -> MVector s a -> MVector s a
+{-# INLINE slice #-}
+slice = G.slice
+
+take :: Prim a => Int -> MVector s a -> MVector s a
+{-# INLINE take #-}
+take = G.take
+
+drop :: Prim a => Int -> MVector s a -> MVector s a
+{-# INLINE drop #-}
+drop = G.drop
+
+splitAt :: Prim a => Int -> MVector s a -> (MVector s a, MVector s a)
+{-# INLINE splitAt #-}
+splitAt = G.splitAt
+
+init :: Prim a => MVector s a -> MVector s a
+{-# INLINE init #-}
+init = G.init
+
+tail :: Prim a => MVector s a -> MVector s a
+{-# INLINE tail #-}
+tail = G.tail
+
+-- | Yield a part of the mutable vector without copying it. No bounds checks
+-- are performed.
+unsafeSlice :: Prim a
+            => Int  -- ^ starting index
+            -> Int  -- ^ length of the slice
+            -> MVector s a
+            -> MVector s a
+{-# INLINE unsafeSlice #-}
+unsafeSlice = G.unsafeSlice
+
+unsafeTake :: Prim a => Int -> MVector s a -> MVector s a
+{-# INLINE unsafeTake #-}
+unsafeTake = G.unsafeTake
+
+unsafeDrop :: Prim a => Int -> MVector s a -> MVector s a
+{-# INLINE unsafeDrop #-}
+unsafeDrop = G.unsafeDrop
+
+unsafeInit :: Prim a => MVector s a -> MVector s a
+{-# INLINE unsafeInit #-}
+unsafeInit = G.unsafeInit
+
+unsafeTail :: Prim a => MVector s a -> MVector s a
+{-# INLINE unsafeTail #-}
+unsafeTail = G.unsafeTail
+
+-- Overlapping
+-- -----------
+
+-- | Check whether two vectors overlap.
+overlaps :: Prim a => MVector s a -> MVector s a -> Bool
+{-# INLINE overlaps #-}
+overlaps = G.overlaps
+
+-- Initialisation
+-- --------------
+
+-- | Create a mutable vector of the given length.
+new :: (PrimMonad m, Prim a) => Int -> m (MVector (PrimState m) a)
+{-# INLINE new #-}
+new = G.new
+
+-- | Create a mutable vector of the given length. The memory is not initialized.
+unsafeNew :: (PrimMonad m, Prim a) => Int -> m (MVector (PrimState m) a)
+{-# INLINE unsafeNew #-}
+unsafeNew = G.unsafeNew
+
+-- | Create a mutable vector of the given length (0 if the length is negative)
+-- and fill it with an initial value.
+replicate :: (PrimMonad m, Prim a) => Int -> a -> m (MVector (PrimState m) a)
+{-# INLINE replicate #-}
+replicate = G.replicate
+
+-- | Create a mutable vector of the given length (0 if the length is negative)
+-- and fill it with values produced by repeatedly executing the monadic action.
+replicateM :: (PrimMonad m, Prim a) => Int -> m a -> m (MVector (PrimState m) a)
+{-# INLINE replicateM #-}
+replicateM = G.replicateM
+
+-- | Create a copy of a mutable vector.
+clone :: (PrimMonad m, Prim a)
+      => MVector (PrimState m) a -> m (MVector (PrimState m) a)
+{-# INLINE clone #-}
+clone = G.clone
+
+-- Growing
+-- -------
+
+-- | Grow a vector by the given number of elements. The number must be
+-- positive.
+grow :: (PrimMonad m, Prim a)
+              => MVector (PrimState m) a -> Int -> m (MVector (PrimState m) a)
+{-# INLINE grow #-}
+grow = G.grow
+
+-- | Grow a vector by the given number of elements. The number must be
+-- positive but this is not checked.
+unsafeGrow :: (PrimMonad m, Prim a)
+               => MVector (PrimState m) a -> Int -> m (MVector (PrimState m) a)
+{-# INLINE unsafeGrow #-}
+unsafeGrow = G.unsafeGrow
+
+-- Restricting memory usage
+-- ------------------------
+
+-- | Reset all elements of the vector to some undefined value, clearing all
+-- references to external objects. This is usually a noop for unboxed vectors.
+clear :: (PrimMonad m, Prim a) => MVector (PrimState m) a -> m ()
+{-# INLINE clear #-}
+clear = G.clear
+
+-- Accessing individual elements
+-- -----------------------------
+
+-- | Yield the element at the given position.
+read :: (PrimMonad m, Prim a) => MVector (PrimState m) a -> Int -> m a
+{-# INLINE read #-}
+read = G.read
+
+-- | Replace the element at the given position.
+write :: (PrimMonad m, Prim a) => MVector (PrimState m) a -> Int -> a -> m ()
+{-# INLINE write #-}
+write = G.write
+
+-- | Modify the element at the given position.
+modify :: (PrimMonad m, Prim a) => MVector (PrimState m) a -> (a -> a) -> Int -> m ()
+{-# INLINE modify #-}
+modify = G.modify
+
+-- | Swap the elements at the given positions.
+swap :: (PrimMonad m, Prim a) => MVector (PrimState m) a -> Int -> Int -> m ()
+{-# INLINE swap #-}
+swap = G.swap
+
+
+-- | Yield the element at the given position. No bounds checks are performed.
+unsafeRead :: (PrimMonad m, Prim a) => MVector (PrimState m) a -> Int -> m a
+{-# INLINE unsafeRead #-}
+unsafeRead = G.unsafeRead
+
+-- | Replace the element at the given position. No bounds checks are performed.
+unsafeWrite
+    :: (PrimMonad m, Prim a) =>  MVector (PrimState m) a -> Int -> a -> m ()
+{-# INLINE unsafeWrite #-}
+unsafeWrite = G.unsafeWrite
+
+-- | Modify the element at the given position. No bounds checks are performed.
+unsafeModify :: (PrimMonad m, Prim a) => MVector (PrimState m) a -> (a -> a) -> Int -> m ()
+{-# INLINE unsafeModify #-}
+unsafeModify = G.unsafeModify
+
+-- | Swap the elements at the given positions. No bounds checks are performed.
+unsafeSwap
+    :: (PrimMonad m, Prim a) => MVector (PrimState m) a -> Int -> Int -> m ()
+{-# INLINE unsafeSwap #-}
+unsafeSwap = G.unsafeSwap
+
+-- Filling and copying
+-- -------------------
+
+-- | Set all elements of the vector to the given value.
+set :: (PrimMonad m, Prim a) => MVector (PrimState m) a -> a -> m ()
+{-# INLINE set #-}
+set = G.set
+
+-- | Copy a vector. The two vectors must have the same length and may not
+-- overlap.
+copy :: (PrimMonad m, Prim a)
+     => MVector (PrimState m) a   -- ^ target
+     -> MVector (PrimState m) a   -- ^ source
+     -> m ()
+{-# INLINE copy #-}
+copy = G.copy
+
+-- | Copy a vector. The two vectors must have the same length and may not
+-- overlap. This is not checked.
+unsafeCopy :: (PrimMonad m, Prim a)
+           => MVector (PrimState m) a   -- ^ target
+           -> MVector (PrimState m) a   -- ^ source
+           -> m ()
+{-# INLINE unsafeCopy #-}
+unsafeCopy = G.unsafeCopy
+
+-- | Move the contents of a vector. The two vectors must have the same
+-- length.
+--
+-- If the vectors do not overlap, then this is equivalent to 'copy'.
+-- Otherwise, the copying is performed as if the source vector were
+-- copied to a temporary vector and then the temporary vector was copied
+-- to the target vector.
+move :: (PrimMonad m, Prim a)
+                 => MVector (PrimState m) a -> MVector (PrimState m) a -> m ()
+{-# INLINE move #-}
+move = G.move
+
+-- | Move the contents of a vector. The two vectors must have the same
+-- length, but this is not checked.
+--
+-- If the vectors do not overlap, then this is equivalent to 'unsafeCopy'.
+-- Otherwise, the copying is performed as if the source vector were
+-- copied to a temporary vector and then the temporary vector was copied
+-- to the target vector.
+unsafeMove :: (PrimMonad m, Prim a)
+                          => MVector (PrimState m) a   -- ^ target
+                          -> MVector (PrimState m) a   -- ^ source
+                          -> m ()
+{-# INLINE unsafeMove #-}
+unsafeMove = G.unsafeMove
+
+-- | Compute the next (lexicographically) permutation of given vector in-place.
+--   Returns False when input is the last permtuation
+nextPermutation :: (PrimMonad m,Ord e,Prim e) => MVector (PrimState m) e -> m Bool
+{-# INLINE nextPermutation #-}
+nextPermutation = G.nextPermutation

third_party/bazel/rules_haskell/examples/vector/Data/Vector/Storable/Internal.hs

@@ -0,0 +1,33 @@
+-- |
+-- Module      : Data.Vector.Storable.Internal
+-- Copyright   : (c) Roman Leshchinskiy 2009-2010
+-- License     : BSD-style
+--
+-- Maintainer  : Roman Leshchinskiy <rl@cse.unsw.edu.au>
+-- Stability   : experimental
+-- Portability : non-portable
+--
+-- Ugly internal utility functions for implementing 'Storable'-based vectors.
+--
+
+module Data.Vector.Storable.Internal (
+  getPtr, setPtr, updPtr
+) where
+
+import Foreign.ForeignPtr
+import Foreign.Ptr
+import GHC.ForeignPtr   ( ForeignPtr(..) )
+import GHC.Ptr          ( Ptr(..) )
+
+getPtr :: ForeignPtr a -> Ptr a
+{-# INLINE getPtr #-}
+getPtr (ForeignPtr addr _) = Ptr addr
+
+setPtr :: ForeignPtr a -> Ptr a -> ForeignPtr a
+{-# INLINE setPtr #-}
+setPtr (ForeignPtr _ c) (Ptr addr) = ForeignPtr addr c
+
+updPtr :: (Ptr a -> Ptr a) -> ForeignPtr a -> ForeignPtr a
+{-# INLINE updPtr #-}
+updPtr f (ForeignPtr p c) = case f (Ptr p) of { Ptr q -> ForeignPtr q c }
+

third_party/bazel/rules_haskell/examples/vector/Data/Vector/Storable/Mutable.hs

@@ -0,0 +1,543 @@
+{-# LANGUAGE CPP, DeriveDataTypeable, FlexibleInstances, MagicHash, MultiParamTypeClasses, ScopedTypeVariables #-}
+
+-- |
+-- Module      : Data.Vector.Storable.Mutable
+-- Copyright   : (c) Roman Leshchinskiy 2009-2010
+-- License     : BSD-style
+--
+-- Maintainer  : Roman Leshchinskiy <rl@cse.unsw.edu.au>
+-- Stability   : experimental
+-- Portability : non-portable
+--
+-- Mutable vectors based on Storable.
+--
+
+module Data.Vector.Storable.Mutable(
+  -- * Mutable vectors of 'Storable' types
+  MVector(..), IOVector, STVector, Storable,
+
+  -- * Accessors
+
+  -- ** Length information
+  length, null,
+
+  -- ** Extracting subvectors
+  slice, init, tail, take, drop, splitAt,
+  unsafeSlice, unsafeInit, unsafeTail, unsafeTake, unsafeDrop,
+
+  -- ** Overlapping
+  overlaps,
+
+  -- * Construction
+
+  -- ** Initialisation
+  new, unsafeNew, replicate, replicateM, clone,
+
+  -- ** Growing
+  grow, unsafeGrow,
+
+  -- ** Restricting memory usage
+  clear,
+
+  -- * Accessing individual elements
+  read, write, modify, swap,
+  unsafeRead, unsafeWrite, unsafeModify, unsafeSwap,
+
+  -- * Modifying vectors
+
+  -- ** Filling and copying
+  set, copy, move, unsafeCopy, unsafeMove,
+
+  -- * Unsafe conversions
+  unsafeCast,
+
+  -- * Raw pointers
+  unsafeFromForeignPtr, unsafeFromForeignPtr0,
+  unsafeToForeignPtr,   unsafeToForeignPtr0,
+  unsafeWith
+) where
+
+import Control.DeepSeq ( NFData(rnf) )
+
+import qualified Data.Vector.Generic.Mutable as G
+import Data.Vector.Storable.Internal
+
+import Foreign.Storable
+import Foreign.ForeignPtr
+
+#if __GLASGOW_HASKELL__ >= 706
+import GHC.ForeignPtr (mallocPlainForeignPtrAlignedBytes)
+#elif __GLASGOW_HASKELL__ >= 700
+import Data.Primitive.ByteArray (MutableByteArray(..), newAlignedPinnedByteArray,
+                                 unsafeFreezeByteArray)
+import GHC.Prim (byteArrayContents#, unsafeCoerce#)
+import GHC.ForeignPtr
+#endif
+
+import Foreign.Ptr
+import Foreign.Marshal.Array ( advancePtr, copyArray, moveArray )
+
+import Control.Monad.Primitive
+import Data.Primitive.Addr
+import Data.Primitive.Types (Prim)
+
+import GHC.Word (Word8, Word16, Word32, Word64)
+import GHC.Ptr (Ptr(..))
+
+import Prelude hiding ( length, null, replicate, reverse, map, read,
+                        take, drop, splitAt, init, tail )
+
+import Data.Typeable ( Typeable )
+
+-- Data.Vector.Internal.Check is not needed
+#define NOT_VECTOR_MODULE
+#include "vector.h"
+
+-- | Mutable 'Storable'-based vectors
+data MVector s a = MVector {-# UNPACK #-} !Int
+                           {-# UNPACK #-} !(ForeignPtr a)
+        deriving ( Typeable )
+
+type IOVector = MVector RealWorld
+type STVector s = MVector s
+
+instance NFData (MVector s a) where
+  rnf (MVector _ _) = ()
+
+instance Storable a => G.MVector MVector a where
+  {-# INLINE basicLength #-}
+  basicLength (MVector n _) = n
+
+  {-# INLINE basicUnsafeSlice #-}
+  basicUnsafeSlice j m (MVector _ fp) = MVector m (updPtr (`advancePtr` j) fp)
+
+  -- FIXME: this relies on non-portable pointer comparisons
+  {-# INLINE basicOverlaps #-}
+  basicOverlaps (MVector m fp) (MVector n fq)
+    = between p q (q `advancePtr` n) || between q p (p `advancePtr` m)
+    where
+      between x y z = x >= y && x < z
+      p = getPtr fp
+      q = getPtr fq
+
+  {-# INLINE basicUnsafeNew #-}
+  basicUnsafeNew n
+    | n < 0 = error $ "Storable.basicUnsafeNew: negative length: " ++ show n
+    | n > mx = error $ "Storable.basicUnsafeNew: length too large: " ++ show n
+    | otherwise = unsafePrimToPrim $ do
+        fp <- mallocVector n
+        return $ MVector n fp
+    where
+      size = sizeOf (undefined :: a)
+      mx = maxBound `quot` size :: Int
+
+  {-# INLINE basicInitialize #-}
+  basicInitialize = storableZero
+
+  {-# INLINE basicUnsafeRead #-}
+  basicUnsafeRead (MVector _ fp) i
+    = unsafePrimToPrim
+    $ withForeignPtr fp (`peekElemOff` i)
+
+  {-# INLINE basicUnsafeWrite #-}
+  basicUnsafeWrite (MVector _ fp) i x
+    = unsafePrimToPrim
+    $ withForeignPtr fp $ \p -> pokeElemOff p i x
+
+  {-# INLINE basicSet #-}
+  basicSet = storableSet
+
+  {-# INLINE basicUnsafeCopy #-}
+  basicUnsafeCopy (MVector n fp) (MVector _ fq)
+    = unsafePrimToPrim
+    $ withForeignPtr fp $ \p ->
+      withForeignPtr fq $ \q ->
+      copyArray p q n
+
+  {-# INLINE basicUnsafeMove #-}
+  basicUnsafeMove (MVector n fp) (MVector _ fq)
+    = unsafePrimToPrim
+    $ withForeignPtr fp $ \p ->
+      withForeignPtr fq $ \q ->
+      moveArray p q n
+
+storableZero :: forall a m. (Storable a, PrimMonad m) => MVector (PrimState m) a -> m ()
+{-# INLINE storableZero #-}
+storableZero (MVector n fp) = unsafePrimToPrim . withForeignPtr fp $ \(Ptr p) -> do
+  let q = Addr p
+  setAddr q byteSize (0 :: Word8)
+ where
+ x :: a
+ x = undefined
+
+ byteSize :: Int
+ byteSize = n * sizeOf x
+
+storableSet :: (Storable a, PrimMonad m) => MVector (PrimState m) a -> a -> m ()
+{-# INLINE storableSet #-}
+storableSet (MVector n fp) x
+  | n == 0 = return ()
+  | otherwise = unsafePrimToPrim $
+                case sizeOf x of
+                  1 -> storableSetAsPrim n fp x (undefined :: Word8)
+                  2 -> storableSetAsPrim n fp x (undefined :: Word16)
+                  4 -> storableSetAsPrim n fp x (undefined :: Word32)
+                  8 -> storableSetAsPrim n fp x (undefined :: Word64)
+                  _ -> withForeignPtr fp $ \p -> do
+                       poke p x
+
+                       let do_set i
+                             | 2*i < n = do
+                                 copyArray (p `advancePtr` i) p i
+                                 do_set (2*i)
+                             | otherwise = copyArray (p `advancePtr` i) p (n-i)
+
+                       do_set 1
+
+storableSetAsPrim
+  :: (Storable a, Prim b) => Int -> ForeignPtr a -> a -> b -> IO ()
+{-# INLINE [0] storableSetAsPrim #-}
+storableSetAsPrim n fp x y = withForeignPtr fp $ \(Ptr p) -> do
+  poke (Ptr p) x
+  let q = Addr p
+  w <- readOffAddr q 0
+  setAddr (q `plusAddr` sizeOf x) (n-1) (w `asTypeOf` y)
+
+{-# INLINE mallocVector #-}
+mallocVector :: Storable a => Int -> IO (ForeignPtr a)
+mallocVector =
+#if __GLASGOW_HASKELL__ >= 706
+  doMalloc undefined
+  where
+    doMalloc :: Storable b => b -> Int -> IO (ForeignPtr b)
+    doMalloc dummy size =
+      mallocPlainForeignPtrAlignedBytes (size * sizeOf dummy) (alignment dummy)
+#elif __GLASGOW_HASKELL__ >= 700
+  doMalloc undefined
+  where
+    doMalloc :: Storable b => b -> Int -> IO (ForeignPtr b)
+    doMalloc dummy size = do
+      arr@(MutableByteArray arr#) <- newAlignedPinnedByteArray arrSize arrAlign
+      newConcForeignPtr
+        (Ptr (byteArrayContents# (unsafeCoerce# arr#)))
+        -- Keep reference to mutable byte array until whole ForeignPtr goes out
+        -- of scope.
+        (touch arr)
+      where
+        arrSize  = size * sizeOf dummy
+        arrAlign = alignment dummy
+#else
+    mallocForeignPtrArray
+#endif
+
+-- Length information
+-- ------------------
+
+-- | Length of the mutable vector.
+length :: Storable a => MVector s a -> Int
+{-# INLINE length #-}
+length = G.length
+
+-- | Check whether the vector is empty
+null :: Storable a => MVector s a -> Bool
+{-# INLINE null #-}
+null = G.null
+
+-- Extracting subvectors
+-- ---------------------
+
+-- | Yield a part of the mutable vector without copying it.
+slice :: Storable a => Int -> Int -> MVector s a -> MVector s a
+{-# INLINE slice #-}
+slice = G.slice
+
+take :: Storable a => Int -> MVector s a -> MVector s a
+{-# INLINE take #-}
+take = G.take
+
+drop :: Storable a => Int -> MVector s a -> MVector s a
+{-# INLINE drop #-}
+drop = G.drop
+
+splitAt :: Storable a => Int -> MVector s a -> (MVector s a, MVector s a)
+{-# INLINE splitAt #-}
+splitAt = G.splitAt
+
+init :: Storable a => MVector s a -> MVector s a
+{-# INLINE init #-}
+init = G.init
+
+tail :: Storable a => MVector s a -> MVector s a
+{-# INLINE tail #-}
+tail = G.tail
+
+-- | Yield a part of the mutable vector without copying it. No bounds checks
+-- are performed.
+unsafeSlice :: Storable a
+            => Int  -- ^ starting index
+            -> Int  -- ^ length of the slice
+            -> MVector s a
+            -> MVector s a
+{-# INLINE unsafeSlice #-}
+unsafeSlice = G.unsafeSlice
+
+unsafeTake :: Storable a => Int -> MVector s a -> MVector s a
+{-# INLINE unsafeTake #-}
+unsafeTake = G.unsafeTake
+
+unsafeDrop :: Storable a => Int -> MVector s a -> MVector s a
+{-# INLINE unsafeDrop #-}
+unsafeDrop = G.unsafeDrop
+
+unsafeInit :: Storable a => MVector s a -> MVector s a
+{-# INLINE unsafeInit #-}
+unsafeInit = G.unsafeInit
+
+unsafeTail :: Storable a => MVector s a -> MVector s a
+{-# INLINE unsafeTail #-}
+unsafeTail = G.unsafeTail
+
+-- Overlapping
+-- -----------
+
+-- | Check whether two vectors overlap.
+overlaps :: Storable a => MVector s a -> MVector s a -> Bool
+{-# INLINE overlaps #-}
+overlaps = G.overlaps
+
+-- Initialisation
+-- --------------
+
+-- | Create a mutable vector of the given length.
+new :: (PrimMonad m, Storable a) => Int -> m (MVector (PrimState m) a)
+{-# INLINE new #-}
+new = G.new
+
+-- | Create a mutable vector of the given length. The memory is not initialized.
+unsafeNew :: (PrimMonad m, Storable a) => Int -> m (MVector (PrimState m) a)
+{-# INLINE unsafeNew #-}
+unsafeNew = G.unsafeNew
+
+-- | Create a mutable vector of the given length (0 if the length is negative)
+-- and fill it with an initial value.
+replicate :: (PrimMonad m, Storable a) => Int -> a -> m (MVector (PrimState m) a)
+{-# INLINE replicate #-}
+replicate = G.replicate
+
+-- | Create a mutable vector of the given length (0 if the length is negative)
+-- and fill it with values produced by repeatedly executing the monadic action.
+replicateM :: (PrimMonad m, Storable a) => Int -> m a -> m (MVector (PrimState m) a)
+{-# INLINE replicateM #-}
+replicateM = G.replicateM
+
+-- | Create a copy of a mutable vector.
+clone :: (PrimMonad m, Storable a)
+      => MVector (PrimState m) a -> m (MVector (PrimState m) a)
+{-# INLINE clone #-}
+clone = G.clone
+
+-- Growing
+-- -------
+
+-- | Grow a vector by the given number of elements. The number must be
+-- positive.
+grow :: (PrimMonad m, Storable a)
+     => MVector (PrimState m) a -> Int -> m (MVector (PrimState m) a)
+{-# INLINE grow #-}
+grow = G.grow
+
+-- | Grow a vector by the given number of elements. The number must be
+-- positive but this is not checked.
+unsafeGrow :: (PrimMonad m, Storable a)
+           => MVector (PrimState m) a -> Int -> m (MVector (PrimState m) a)
+{-# INLINE unsafeGrow #-}
+unsafeGrow = G.unsafeGrow
+
+-- Restricting memory usage
+-- ------------------------
+
+-- | Reset all elements of the vector to some undefined value, clearing all
+-- references to external objects. This is usually a noop for unboxed vectors.
+clear :: (PrimMonad m, Storable a) => MVector (PrimState m) a -> m ()
+{-# INLINE clear #-}
+clear = G.clear
+
+-- Accessing individual elements
+-- -----------------------------
+
+-- | Yield the element at the given position.
+read :: (PrimMonad m, Storable a) => MVector (PrimState m) a -> Int -> m a
+{-# INLINE read #-}
+read = G.read
+
+-- | Replace the element at the given position.
+write
+    :: (PrimMonad m, Storable a) => MVector (PrimState m) a -> Int -> a -> m ()
+{-# INLINE write #-}
+write = G.write
+
+-- | Modify the element at the given position.
+modify :: (PrimMonad m, Storable a) => MVector (PrimState m) a -> (a -> a) -> Int -> m ()
+{-# INLINE modify #-}
+modify = G.modify
+
+-- | Swap the elements at the given positions.
+swap
+    :: (PrimMonad m, Storable a) => MVector (PrimState m) a -> Int -> Int -> m ()
+{-# INLINE swap #-}
+swap = G.swap
+
+
+-- | Yield the element at the given position. No bounds checks are performed.
+unsafeRead :: (PrimMonad m, Storable a) => MVector (PrimState m) a -> Int -> m a
+{-# INLINE unsafeRead #-}
+unsafeRead = G.unsafeRead
+
+-- | Replace the element at the given position. No bounds checks are performed.
+unsafeWrite
+    :: (PrimMonad m, Storable a) =>  MVector (PrimState m) a -> Int -> a -> m ()
+{-# INLINE unsafeWrite #-}
+unsafeWrite = G.unsafeWrite
+
+-- | Modify the element at the given position. No bounds checks are performed.
+unsafeModify :: (PrimMonad m, Storable a) => MVector (PrimState m) a -> (a -> a) -> Int -> m ()
+{-# INLINE unsafeModify #-}
+unsafeModify = G.unsafeModify
+
+-- | Swap the elements at the given positions. No bounds checks are performed.
+unsafeSwap
+    :: (PrimMonad m, Storable a) => MVector (PrimState m) a -> Int -> Int -> m ()
+{-# INLINE unsafeSwap #-}
+unsafeSwap = G.unsafeSwap
+
+-- Filling and copying
+-- -------------------
+
+-- | Set all elements of the vector to the given value.
+set :: (PrimMonad m, Storable a) => MVector (PrimState m) a -> a -> m ()
+{-# INLINE set #-}
+set = G.set
+
+-- | Copy a vector. The two vectors must have the same length and may not
+-- overlap.
+copy :: (PrimMonad m, Storable a)
+     => MVector (PrimState m) a   -- ^ target
+     -> MVector (PrimState m) a   -- ^ source
+     -> m ()
+{-# INLINE copy #-}
+copy = G.copy
+
+-- | Copy a vector. The two vectors must have the same length and may not
+-- overlap. This is not checked.
+unsafeCopy :: (PrimMonad m, Storable a)
+           => MVector (PrimState m) a   -- ^ target
+           -> MVector (PrimState m) a   -- ^ source
+           -> m ()
+{-# INLINE unsafeCopy #-}
+unsafeCopy = G.unsafeCopy
+
+-- | Move the contents of a vector. The two vectors must have the same
+-- length.
+--
+-- If the vectors do not overlap, then this is equivalent to 'copy'.
+-- Otherwise, the copying is performed as if the source vector were
+-- copied to a temporary vector and then the temporary vector was copied
+-- to the target vector.
+move :: (PrimMonad m, Storable a)
+     => MVector (PrimState m) a -> MVector (PrimState m) a -> m ()
+{-# INLINE move #-}
+move = G.move
+
+-- | Move the contents of a vector. The two vectors must have the same
+-- length, but this is not checked.
+--
+-- If the vectors do not overlap, then this is equivalent to 'unsafeCopy'.
+-- Otherwise, the copying is performed as if the source vector were
+-- copied to a temporary vector and then the temporary vector was copied
+-- to the target vector.
+unsafeMove :: (PrimMonad m, Storable a)
+           => MVector (PrimState m) a   -- ^ target
+           -> MVector (PrimState m) a   -- ^ source
+           -> m ()
+{-# INLINE unsafeMove #-}
+unsafeMove = G.unsafeMove
+
+-- Unsafe conversions
+-- ------------------
+
+-- | /O(1)/ Unsafely cast a mutable vector from one element type to another.
+-- The operation just changes the type of the underlying pointer and does not
+-- modify the elements.
+--
+-- The resulting vector contains as many elements as can fit into the
+-- underlying memory block.
+--
+unsafeCast :: forall a b s.
+              (Storable a, Storable b) => MVector s a -> MVector s b
+{-# INLINE unsafeCast #-}
+unsafeCast (MVector n fp)
+  = MVector ((n * sizeOf (undefined :: a)) `div` sizeOf (undefined :: b))
+            (castForeignPtr fp)
+
+-- Raw pointers
+-- ------------
+
+-- | Create a mutable vector from a 'ForeignPtr' with an offset and a length.
+--
+-- Modifying data through the 'ForeignPtr' afterwards is unsafe if the vector
+-- could have been frozen before the modification.
+--
+--  If your offset is 0 it is more efficient to use 'unsafeFromForeignPtr0'.
+unsafeFromForeignPtr :: Storable a
+                     => ForeignPtr a    -- ^ pointer
+                     -> Int             -- ^ offset
+                     -> Int             -- ^ length
+                     -> MVector s a
+{-# INLINE_FUSED unsafeFromForeignPtr #-}
+unsafeFromForeignPtr fp i n = unsafeFromForeignPtr0 fp' n
+    where
+      fp' = updPtr (`advancePtr` i) fp
+
+{-# RULES
+"unsafeFromForeignPtr fp 0 n -> unsafeFromForeignPtr0 fp n " forall fp n.
+  unsafeFromForeignPtr fp 0 n = unsafeFromForeignPtr0 fp n   #-}
+
+
+-- | /O(1)/ Create a mutable vector from a 'ForeignPtr' and a length.
+--
+-- It is assumed the pointer points directly to the data (no offset).
+-- Use `unsafeFromForeignPtr` if you need to specify an offset.
+--
+-- Modifying data through the 'ForeignPtr' afterwards is unsafe if the vector
+-- could have been frozen before the modification.
+unsafeFromForeignPtr0 :: Storable a
+                      => ForeignPtr a    -- ^ pointer
+                      -> Int             -- ^ length
+                      -> MVector s a
+{-# INLINE unsafeFromForeignPtr0 #-}
+unsafeFromForeignPtr0 fp n = MVector n fp
+
+-- | Yield the underlying 'ForeignPtr' together with the offset to the data
+-- and its length. Modifying the data through the 'ForeignPtr' is
+-- unsafe if the vector could have frozen before the modification.
+unsafeToForeignPtr :: Storable a => MVector s a -> (ForeignPtr a, Int, Int)
+{-# INLINE unsafeToForeignPtr #-}
+unsafeToForeignPtr (MVector n fp) = (fp, 0, n)
+
+-- | /O(1)/ Yield the underlying 'ForeignPtr' together with its length.
+--
+-- You can assume the pointer points directly to the data (no offset).
+--
+-- Modifying the data through the 'ForeignPtr' is unsafe if the vector could
+-- have frozen before the modification.
+unsafeToForeignPtr0 :: Storable a => MVector s a -> (ForeignPtr a, Int)
+{-# INLINE unsafeToForeignPtr0 #-}
+unsafeToForeignPtr0 (MVector n fp) = (fp, n)
+
+-- | Pass a pointer to the vector's data to the IO action. Modifying data
+-- through the pointer is unsafe if the vector could have been frozen before
+-- the modification.
+unsafeWith :: Storable a => IOVector a -> (Ptr a -> IO b) -> IO b
+{-# INLINE unsafeWith #-}
+unsafeWith (MVector _ fp) = withForeignPtr fp
+

third_party/bazel/rules_haskell/examples/vector/Data/Vector/Unboxed/Base.hs

@@ -0,0 +1,408 @@
+{-# LANGUAGE BangPatterns, CPP, MultiParamTypeClasses, TypeFamilies, FlexibleContexts #-}
+#if __GLASGOW_HASKELL__ >= 707
+{-# LANGUAGE DeriveDataTypeable, StandaloneDeriving #-}
+#endif
+{-# OPTIONS_HADDOCK hide #-}
+
+-- |
+-- Module      : Data.Vector.Unboxed.Base
+-- Copyright   : (c) Roman Leshchinskiy 2009-2010
+-- License     : BSD-style
+--
+-- Maintainer  : Roman Leshchinskiy <rl@cse.unsw.edu.au>
+-- Stability   : experimental
+-- Portability : non-portable
+--
+-- Adaptive unboxed vectors: basic implementation
+--
+
+module Data.Vector.Unboxed.Base (
+  MVector(..), IOVector, STVector, Vector(..), Unbox
+) where
+
+import qualified Data.Vector.Generic         as G
+import qualified Data.Vector.Generic.Mutable as M
+
+import qualified Data.Vector.Primitive as P
+
+import Control.DeepSeq ( NFData(rnf) )
+
+import Control.Monad.Primitive
+import Control.Monad ( liftM )
+
+import Data.Word ( Word8, Word16, Word32, Word64 )
+import Data.Int  ( Int8, Int16, Int32, Int64 )
+import Data.Complex
+
+#if !MIN_VERSION_base(4,8,0)
+import Data.Word ( Word )
+#endif
+
+#if __GLASGOW_HASKELL__ >= 707
+import Data.Typeable ( Typeable )
+#else
+import Data.Typeable ( Typeable1(..), Typeable2(..), mkTyConApp,
+                       mkTyCon3
+                     )
+#endif
+
+import Data.Data     ( Data(..) )
+
+-- Data.Vector.Internal.Check is unused
+#define NOT_VECTOR_MODULE
+#include "vector.h"
+
+data family MVector s a
+data family Vector    a
+
+type IOVector = MVector RealWorld
+type STVector s = MVector s
+
+type instance G.Mutable Vector = MVector
+
+class (G.Vector Vector a, M.MVector MVector a) => Unbox a
+
+instance NFData (Vector a) where rnf !_ = ()
+instance NFData (MVector s a) where rnf !_ = ()
+
+-- -----------------
+-- Data and Typeable
+-- -----------------
+#if __GLASGOW_HASKELL__ >= 707
+deriving instance Typeable Vector
+deriving instance Typeable MVector
+#else
+vectorTyCon = mkTyCon3 "vector"
+
+instance Typeable1 Vector where
+  typeOf1 _ = mkTyConApp (vectorTyCon "Data.Vector.Unboxed" "Vector") []
+
+instance Typeable2 MVector where
+  typeOf2 _ = mkTyConApp (vectorTyCon "Data.Vector.Unboxed.Mutable" "MVector") []
+#endif
+
+instance (Data a, Unbox a) => Data (Vector a) where
+  gfoldl       = G.gfoldl
+  toConstr _   = error "toConstr"
+  gunfold _ _  = error "gunfold"
+  dataTypeOf _ = G.mkType "Data.Vector.Unboxed.Vector"
+  dataCast1    = G.dataCast
+
+-- ----
+-- Unit
+-- ----
+
+newtype instance MVector s () = MV_Unit Int
+newtype instance Vector    () = V_Unit Int
+
+instance Unbox ()
+
+instance M.MVector MVector () where
+  {-# INLINE basicLength #-}
+  {-# INLINE basicUnsafeSlice #-}
+  {-# INLINE basicOverlaps #-}
+  {-# INLINE basicUnsafeNew #-}
+  {-# INLINE basicInitialize #-}
+  {-# INLINE basicUnsafeRead #-}
+  {-# INLINE basicUnsafeWrite #-}
+  {-# INLINE basicClear #-}
+  {-# INLINE basicSet #-}
+  {-# INLINE basicUnsafeCopy #-}
+  {-# INLINE basicUnsafeGrow #-}
+
+  basicLength (MV_Unit n) = n
+
+  basicUnsafeSlice _ m (MV_Unit _) = MV_Unit m
+
+  basicOverlaps _ _ = False
+
+  basicUnsafeNew n = return (MV_Unit n)
+
+  -- Nothing to initialize
+  basicInitialize _ = return ()
+
+  basicUnsafeRead (MV_Unit _) _ = return ()
+
+  basicUnsafeWrite (MV_Unit _) _ () = return ()
+
+  basicClear _ = return ()
+
+  basicSet (MV_Unit _) () = return ()
+
+  basicUnsafeCopy (MV_Unit _) (MV_Unit _) = return ()
+
+  basicUnsafeGrow (MV_Unit n) m = return $ MV_Unit (n+m)
+
+instance G.Vector Vector () where
+  {-# INLINE basicUnsafeFreeze #-}
+  basicUnsafeFreeze (MV_Unit n) = return $ V_Unit n
+
+  {-# INLINE basicUnsafeThaw #-}
+  basicUnsafeThaw (V_Unit n) = return $ MV_Unit n
+
+  {-# INLINE basicLength #-}
+  basicLength (V_Unit n) = n
+
+  {-# INLINE basicUnsafeSlice #-}
+  basicUnsafeSlice _ m (V_Unit _) = V_Unit m
+
+  {-# INLINE basicUnsafeIndexM #-}
+  basicUnsafeIndexM (V_Unit _) _ = return ()
+
+  {-# INLINE basicUnsafeCopy #-}
+  basicUnsafeCopy (MV_Unit _) (V_Unit _) = return ()
+
+  {-# INLINE elemseq #-}
+  elemseq _ = seq
+
+
+-- ---------------
+-- Primitive types
+-- ---------------
+
+#define primMVector(ty,con)                                             \
+instance M.MVector MVector ty where {                                   \
+  {-# INLINE basicLength #-}                                            \
+; {-# INLINE basicUnsafeSlice #-}                                       \
+; {-# INLINE basicOverlaps #-}                                          \
+; {-# INLINE basicUnsafeNew #-}                                         \
+; {-# INLINE basicInitialize #-}                                        \
+; {-# INLINE basicUnsafeReplicate #-}                                   \
+; {-# INLINE basicUnsafeRead #-}                                        \
+; {-# INLINE basicUnsafeWrite #-}                                       \
+; {-# INLINE basicClear #-}                                             \
+; {-# INLINE basicSet #-}                                               \
+; {-# INLINE basicUnsafeCopy #-}                                        \
+; {-# INLINE basicUnsafeGrow #-}                                        \
+; basicLength (con v) = M.basicLength v                                 \
+; basicUnsafeSlice i n (con v) = con $ M.basicUnsafeSlice i n v         \
+; basicOverlaps (con v1) (con v2) = M.basicOverlaps v1 v2               \
+; basicUnsafeNew n = con `liftM` M.basicUnsafeNew n                     \
+; basicInitialize (con v) = M.basicInitialize v                         \
+; basicUnsafeReplicate n x = con `liftM` M.basicUnsafeReplicate n x     \
+; basicUnsafeRead (con v) i = M.basicUnsafeRead v i                     \
+; basicUnsafeWrite (con v) i x = M.basicUnsafeWrite v i x               \
+; basicClear (con v) = M.basicClear v                                   \
+; basicSet (con v) x = M.basicSet v x                                   \
+; basicUnsafeCopy (con v1) (con v2) = M.basicUnsafeCopy v1 v2           \
+; basicUnsafeMove (con v1) (con v2) = M.basicUnsafeMove v1 v2           \
+; basicUnsafeGrow (con v) n = con `liftM` M.basicUnsafeGrow v n }
+
+#define primVector(ty,con,mcon)                                         \
+instance G.Vector Vector ty where {                                     \
+  {-# INLINE basicUnsafeFreeze #-}                                      \
+; {-# INLINE basicUnsafeThaw #-}                                        \
+; {-# INLINE basicLength #-}                                            \
+; {-# INLINE basicUnsafeSlice #-}                                       \
+; {-# INLINE basicUnsafeIndexM #-}                                      \
+; {-# INLINE elemseq #-}                                                \
+; basicUnsafeFreeze (mcon v) = con `liftM` G.basicUnsafeFreeze v        \
+; basicUnsafeThaw (con v) = mcon `liftM` G.basicUnsafeThaw v            \
+; basicLength (con v) = G.basicLength v                                 \
+; basicUnsafeSlice i n (con v) = con $ G.basicUnsafeSlice i n v         \
+; basicUnsafeIndexM (con v) i = G.basicUnsafeIndexM v i                 \
+; basicUnsafeCopy (mcon mv) (con v) = G.basicUnsafeCopy mv v            \
+; elemseq _ = seq }
+
+newtype instance MVector s Int = MV_Int (P.MVector s Int)
+newtype instance Vector    Int = V_Int  (P.Vector    Int)
+instance Unbox Int
+primMVector(Int, MV_Int)
+primVector(Int, V_Int, MV_Int)
+
+newtype instance MVector s Int8 = MV_Int8 (P.MVector s Int8)
+newtype instance Vector    Int8 = V_Int8  (P.Vector    Int8)
+instance Unbox Int8
+primMVector(Int8, MV_Int8)
+primVector(Int8, V_Int8, MV_Int8)
+
+newtype instance MVector s Int16 = MV_Int16 (P.MVector s Int16)
+newtype instance Vector    Int16 = V_Int16  (P.Vector    Int16)
+instance Unbox Int16
+primMVector(Int16, MV_Int16)
+primVector(Int16, V_Int16, MV_Int16)
+
+newtype instance MVector s Int32 = MV_Int32 (P.MVector s Int32)
+newtype instance Vector    Int32 = V_Int32  (P.Vector    Int32)
+instance Unbox Int32
+primMVector(Int32, MV_Int32)
+primVector(Int32, V_Int32, MV_Int32)
+
+newtype instance MVector s Int64 = MV_Int64 (P.MVector s Int64)
+newtype instance Vector    Int64 = V_Int64  (P.Vector    Int64)
+instance Unbox Int64
+primMVector(Int64, MV_Int64)
+primVector(Int64, V_Int64, MV_Int64)
+
+
+newtype instance MVector s Word = MV_Word (P.MVector s Word)
+newtype instance Vector    Word = V_Word  (P.Vector    Word)
+instance Unbox Word
+primMVector(Word, MV_Word)
+primVector(Word, V_Word, MV_Word)
+
+newtype instance MVector s Word8 = MV_Word8 (P.MVector s Word8)
+newtype instance Vector    Word8 = V_Word8  (P.Vector    Word8)
+instance Unbox Word8
+primMVector(Word8, MV_Word8)
+primVector(Word8, V_Word8, MV_Word8)
+
+newtype instance MVector s Word16 = MV_Word16 (P.MVector s Word16)
+newtype instance Vector    Word16 = V_Word16  (P.Vector    Word16)
+instance Unbox Word16
+primMVector(Word16, MV_Word16)
+primVector(Word16, V_Word16, MV_Word16)
+
+newtype instance MVector s Word32 = MV_Word32 (P.MVector s Word32)
+newtype instance Vector    Word32 = V_Word32  (P.Vector    Word32)
+instance Unbox Word32
+primMVector(Word32, MV_Word32)
+primVector(Word32, V_Word32, MV_Word32)
+
+newtype instance MVector s Word64 = MV_Word64 (P.MVector s Word64)
+newtype instance Vector    Word64 = V_Word64  (P.Vector    Word64)
+instance Unbox Word64
+primMVector(Word64, MV_Word64)
+primVector(Word64, V_Word64, MV_Word64)
+
+
+newtype instance MVector s Float = MV_Float (P.MVector s Float)
+newtype instance Vector    Float = V_Float  (P.Vector    Float)
+instance Unbox Float
+primMVector(Float, MV_Float)
+primVector(Float, V_Float, MV_Float)
+
+newtype instance MVector s Double = MV_Double (P.MVector s Double)
+newtype instance Vector    Double = V_Double  (P.Vector    Double)
+instance Unbox Double
+primMVector(Double, MV_Double)
+primVector(Double, V_Double, MV_Double)
+
+
+newtype instance MVector s Char = MV_Char (P.MVector s Char)
+newtype instance Vector    Char = V_Char  (P.Vector    Char)
+instance Unbox Char
+primMVector(Char, MV_Char)
+primVector(Char, V_Char, MV_Char)
+
+-- ----
+-- Bool
+-- ----
+
+fromBool :: Bool -> Word8
+{-# INLINE fromBool #-}
+fromBool True = 1
+fromBool False = 0
+
+toBool :: Word8 -> Bool
+{-# INLINE toBool #-}
+toBool 0 = False
+toBool _ = True
+
+newtype instance MVector s Bool = MV_Bool (P.MVector s Word8)
+newtype instance Vector    Bool = V_Bool  (P.Vector    Word8)
+
+instance Unbox Bool
+
+instance M.MVector MVector Bool where
+  {-# INLINE basicLength #-}
+  {-# INLINE basicUnsafeSlice #-}
+  {-# INLINE basicOverlaps #-}
+  {-# INLINE basicUnsafeNew #-}
+  {-# INLINE basicInitialize #-}
+  {-# INLINE basicUnsafeReplicate #-}
+  {-# INLINE basicUnsafeRead #-}
+  {-# INLINE basicUnsafeWrite #-}
+  {-# INLINE basicClear #-}
+  {-# INLINE basicSet #-}
+  {-# INLINE basicUnsafeCopy #-}
+  {-# INLINE basicUnsafeGrow #-}
+  basicLength (MV_Bool v) = M.basicLength v
+  basicUnsafeSlice i n (MV_Bool v) = MV_Bool $ M.basicUnsafeSlice i n v
+  basicOverlaps (MV_Bool v1) (MV_Bool v2) = M.basicOverlaps v1 v2
+  basicUnsafeNew n = MV_Bool `liftM` M.basicUnsafeNew n
+  basicInitialize (MV_Bool v) = M.basicInitialize v
+  basicUnsafeReplicate n x = MV_Bool `liftM` M.basicUnsafeReplicate n (fromBool x)
+  basicUnsafeRead (MV_Bool v) i = toBool `liftM` M.basicUnsafeRead v i
+  basicUnsafeWrite (MV_Bool v) i x = M.basicUnsafeWrite v i (fromBool x)
+  basicClear (MV_Bool v) = M.basicClear v
+  basicSet (MV_Bool v) x = M.basicSet v (fromBool x)
+  basicUnsafeCopy (MV_Bool v1) (MV_Bool v2) = M.basicUnsafeCopy v1 v2
+  basicUnsafeMove (MV_Bool v1) (MV_Bool v2) = M.basicUnsafeMove v1 v2
+  basicUnsafeGrow (MV_Bool v) n = MV_Bool `liftM` M.basicUnsafeGrow v n
+
+instance G.Vector Vector Bool where
+  {-# INLINE basicUnsafeFreeze #-}
+  {-# INLINE basicUnsafeThaw #-}
+  {-# INLINE basicLength #-}
+  {-# INLINE basicUnsafeSlice #-}
+  {-# INLINE basicUnsafeIndexM #-}
+  {-# INLINE elemseq #-}
+  basicUnsafeFreeze (MV_Bool v) = V_Bool `liftM` G.basicUnsafeFreeze v
+  basicUnsafeThaw (V_Bool v) = MV_Bool `liftM` G.basicUnsafeThaw v
+  basicLength (V_Bool v) = G.basicLength v
+  basicUnsafeSlice i n (V_Bool v) = V_Bool $ G.basicUnsafeSlice i n v
+  basicUnsafeIndexM (V_Bool v) i = toBool `liftM` G.basicUnsafeIndexM v i
+  basicUnsafeCopy (MV_Bool mv) (V_Bool v) = G.basicUnsafeCopy mv v
+  elemseq _ = seq
+
+-- -------
+-- Complex
+-- -------
+
+newtype instance MVector s (Complex a) = MV_Complex (MVector s (a,a))
+newtype instance Vector    (Complex a) = V_Complex  (Vector    (a,a))
+
+instance (Unbox a) => Unbox (Complex a)
+
+instance (Unbox a) => M.MVector MVector (Complex a) where
+  {-# INLINE basicLength #-}
+  {-# INLINE basicUnsafeSlice #-}
+  {-# INLINE basicOverlaps #-}
+  {-# INLINE basicUnsafeNew #-}
+  {-# INLINE basicInitialize #-}
+  {-# INLINE basicUnsafeReplicate #-}
+  {-# INLINE basicUnsafeRead #-}
+  {-# INLINE basicUnsafeWrite #-}
+  {-# INLINE basicClear #-}
+  {-# INLINE basicSet #-}
+  {-# INLINE basicUnsafeCopy #-}
+  {-# INLINE basicUnsafeGrow #-}
+  basicLength (MV_Complex v) = M.basicLength v
+  basicUnsafeSlice i n (MV_Complex v) = MV_Complex $ M.basicUnsafeSlice i n v
+  basicOverlaps (MV_Complex v1) (MV_Complex v2) = M.basicOverlaps v1 v2
+  basicUnsafeNew n = MV_Complex `liftM` M.basicUnsafeNew n
+  basicInitialize (MV_Complex v) = M.basicInitialize v
+  basicUnsafeReplicate n (x :+ y) = MV_Complex `liftM` M.basicUnsafeReplicate n (x,y)
+  basicUnsafeRead (MV_Complex v) i = uncurry (:+) `liftM` M.basicUnsafeRead v i
+  basicUnsafeWrite (MV_Complex v) i (x :+ y) = M.basicUnsafeWrite v i (x,y)
+  basicClear (MV_Complex v) = M.basicClear v
+  basicSet (MV_Complex v) (x :+ y) = M.basicSet v (x,y)
+  basicUnsafeCopy (MV_Complex v1) (MV_Complex v2) = M.basicUnsafeCopy v1 v2
+  basicUnsafeMove (MV_Complex v1) (MV_Complex v2) = M.basicUnsafeMove v1 v2
+  basicUnsafeGrow (MV_Complex v) n = MV_Complex `liftM` M.basicUnsafeGrow v n
+
+instance (Unbox a) => G.Vector Vector (Complex a) where
+  {-# INLINE basicUnsafeFreeze #-}
+  {-# INLINE basicUnsafeThaw #-}
+  {-# INLINE basicLength #-}
+  {-# INLINE basicUnsafeSlice #-}
+  {-# INLINE basicUnsafeIndexM #-}
+  {-# INLINE elemseq #-}
+  basicUnsafeFreeze (MV_Complex v) = V_Complex `liftM` G.basicUnsafeFreeze v
+  basicUnsafeThaw (V_Complex v) = MV_Complex `liftM` G.basicUnsafeThaw v
+  basicLength (V_Complex v) = G.basicLength v
+  basicUnsafeSlice i n (V_Complex v) = V_Complex $ G.basicUnsafeSlice i n v
+  basicUnsafeIndexM (V_Complex v) i
+                = uncurry (:+) `liftM` G.basicUnsafeIndexM v i
+  basicUnsafeCopy (MV_Complex mv) (V_Complex v)
+                = G.basicUnsafeCopy mv v
+  elemseq _ (x :+ y) z = G.elemseq (undefined :: Vector a) x
+                       $ G.elemseq (undefined :: Vector a) y z
+
+-- ------
+-- Tuples
+-- ------
+
+#define DEFINE_INSTANCES
+#include "unbox-tuple-instances"

third_party/bazel/rules_haskell/examples/vector/Data/Vector/Unboxed/Mutable.hs

@@ -0,0 +1,307 @@
+{-# LANGUAGE CPP #-}
+
+-- |
+-- Module      : Data.Vector.Unboxed.Mutable
+-- Copyright   : (c) Roman Leshchinskiy 2009-2010
+-- License     : BSD-style
+--
+-- Maintainer  : Roman Leshchinskiy <rl@cse.unsw.edu.au>
+-- Stability   : experimental
+-- Portability : non-portable
+--
+-- Mutable adaptive unboxed vectors
+--
+
+module Data.Vector.Unboxed.Mutable (
+  -- * Mutable vectors of primitive types
+  MVector(..), IOVector, STVector, Unbox,
+
+  -- * Accessors
+
+  -- ** Length information
+  length, null,
+
+  -- ** Extracting subvectors
+  slice, init, tail, take, drop, splitAt,
+  unsafeSlice, unsafeInit, unsafeTail, unsafeTake, unsafeDrop,
+
+  -- ** Overlapping
+  overlaps,
+
+  -- * Construction
+
+  -- ** Initialisation
+  new, unsafeNew, replicate, replicateM, clone,
+
+  -- ** Growing
+  grow, unsafeGrow,
+
+  -- ** Restricting memory usage
+  clear,
+
+  -- * Zipping and unzipping
+  zip, zip3, zip4, zip5, zip6,
+  unzip, unzip3, unzip4, unzip5, unzip6,
+
+  -- * Accessing individual elements
+  read, write, modify, swap,
+  unsafeRead, unsafeWrite, unsafeModify, unsafeSwap,
+
+  -- * Modifying vectors
+  nextPermutation,
+
+  -- ** Filling and copying
+  set, copy, move, unsafeCopy, unsafeMove
+) where
+
+import Data.Vector.Unboxed.Base
+import qualified Data.Vector.Generic.Mutable as G
+import Data.Vector.Fusion.Util ( delayed_min )
+import Control.Monad.Primitive
+
+import Prelude hiding ( length, null, replicate, reverse, map, read,
+                        take, drop, splitAt, init, tail,
+                        zip, zip3, unzip, unzip3 )
+
+-- don't import an unused Data.Vector.Internal.Check
+#define NOT_VECTOR_MODULE
+#include "vector.h"
+
+-- Length information
+-- ------------------
+
+-- | Length of the mutable vector.
+length :: Unbox a => MVector s a -> Int
+{-# INLINE length #-}
+length = G.length
+
+-- | Check whether the vector is empty
+null :: Unbox a => MVector s a -> Bool
+{-# INLINE null #-}
+null = G.null
+
+-- Extracting subvectors
+-- ---------------------
+
+-- | Yield a part of the mutable vector without copying it.
+slice :: Unbox a => Int -> Int -> MVector s a -> MVector s a
+{-# INLINE slice #-}
+slice = G.slice
+
+take :: Unbox a => Int -> MVector s a -> MVector s a
+{-# INLINE take #-}
+take = G.take
+
+drop :: Unbox a => Int -> MVector s a -> MVector s a
+{-# INLINE drop #-}
+drop = G.drop
+
+splitAt :: Unbox a => Int -> MVector s a -> (MVector s a, MVector s a)
+{-# INLINE splitAt #-}
+splitAt = G.splitAt
+
+init :: Unbox a => MVector s a -> MVector s a
+{-# INLINE init #-}
+init = G.init
+
+tail :: Unbox a => MVector s a -> MVector s a
+{-# INLINE tail #-}
+tail = G.tail
+
+-- | Yield a part of the mutable vector without copying it. No bounds checks
+-- are performed.
+unsafeSlice :: Unbox a
+            => Int  -- ^ starting index
+            -> Int  -- ^ length of the slice
+            -> MVector s a
+            -> MVector s a
+{-# INLINE unsafeSlice #-}
+unsafeSlice = G.unsafeSlice
+
+unsafeTake :: Unbox a => Int -> MVector s a -> MVector s a
+{-# INLINE unsafeTake #-}
+unsafeTake = G.unsafeTake
+
+unsafeDrop :: Unbox a => Int -> MVector s a -> MVector s a
+{-# INLINE unsafeDrop #-}
+unsafeDrop = G.unsafeDrop
+
+unsafeInit :: Unbox a => MVector s a -> MVector s a
+{-# INLINE unsafeInit #-}
+unsafeInit = G.unsafeInit
+
+unsafeTail :: Unbox a => MVector s a -> MVector s a
+{-# INLINE unsafeTail #-}
+unsafeTail = G.unsafeTail
+
+-- Overlapping
+-- -----------
+
+-- | Check whether two vectors overlap.
+overlaps :: Unbox a => MVector s a -> MVector s a -> Bool
+{-# INLINE overlaps #-}
+overlaps = G.overlaps
+
+-- Initialisation
+-- --------------
+
+-- | Create a mutable vector of the given length.
+new :: (PrimMonad m, Unbox a) => Int -> m (MVector (PrimState m) a)
+{-# INLINE new #-}
+new = G.new
+
+-- | Create a mutable vector of the given length. The memory is not initialized.
+unsafeNew :: (PrimMonad m, Unbox a) => Int -> m (MVector (PrimState m) a)
+{-# INLINE unsafeNew #-}
+unsafeNew = G.unsafeNew
+
+-- | Create a mutable vector of the given length (0 if the length is negative)
+-- and fill it with an initial value.
+replicate :: (PrimMonad m, Unbox a) => Int -> a -> m (MVector (PrimState m) a)
+{-# INLINE replicate #-}
+replicate = G.replicate
+
+-- | Create a mutable vector of the given length (0 if the length is negative)
+-- and fill it with values produced by repeatedly executing the monadic action.
+replicateM :: (PrimMonad m, Unbox a) => Int -> m a -> m (MVector (PrimState m) a)
+{-# INLINE replicateM #-}
+replicateM = G.replicateM
+
+-- | Create a copy of a mutable vector.
+clone :: (PrimMonad m, Unbox a)
+      => MVector (PrimState m) a -> m (MVector (PrimState m) a)
+{-# INLINE clone #-}
+clone = G.clone
+
+-- Growing
+-- -------
+
+-- | Grow a vector by the given number of elements. The number must be
+-- positive.
+grow :: (PrimMonad m, Unbox a)
+              => MVector (PrimState m) a -> Int -> m (MVector (PrimState m) a)
+{-# INLINE grow #-}
+grow = G.grow
+
+-- | Grow a vector by the given number of elements. The number must be
+-- positive but this is not checked.
+unsafeGrow :: (PrimMonad m, Unbox a)
+               => MVector (PrimState m) a -> Int -> m (MVector (PrimState m) a)
+{-# INLINE unsafeGrow #-}
+unsafeGrow = G.unsafeGrow
+
+-- Restricting memory usage
+-- ------------------------
+
+-- | Reset all elements of the vector to some undefined value, clearing all
+-- references to external objects. This is usually a noop for unboxed vectors.
+clear :: (PrimMonad m, Unbox a) => MVector (PrimState m) a -> m ()
+{-# INLINE clear #-}
+clear = G.clear
+
+-- Accessing individual elements
+-- -----------------------------
+
+-- | Yield the element at the given position.
+read :: (PrimMonad m, Unbox a) => MVector (PrimState m) a -> Int -> m a
+{-# INLINE read #-}
+read = G.read
+
+-- | Replace the element at the given position.
+write :: (PrimMonad m, Unbox a) => MVector (PrimState m) a -> Int -> a -> m ()
+{-# INLINE write #-}
+write = G.write
+
+-- | Modify the element at the given position.
+modify :: (PrimMonad m, Unbox a) => MVector (PrimState m) a -> (a -> a) -> Int -> m ()
+{-# INLINE modify #-}
+modify = G.modify
+
+-- | Swap the elements at the given positions.
+swap :: (PrimMonad m, Unbox a) => MVector (PrimState m) a -> Int -> Int -> m ()
+{-# INLINE swap #-}
+swap = G.swap
+
+
+-- | Yield the element at the given position. No bounds checks are performed.
+unsafeRead :: (PrimMonad m, Unbox a) => MVector (PrimState m) a -> Int -> m a
+{-# INLINE unsafeRead #-}
+unsafeRead = G.unsafeRead
+
+-- | Replace the element at the given position. No bounds checks are performed.
+unsafeWrite
+    :: (PrimMonad m, Unbox a) =>  MVector (PrimState m) a -> Int -> a -> m ()
+{-# INLINE unsafeWrite #-}
+unsafeWrite = G.unsafeWrite
+
+-- | Modify the element at the given position. No bounds checks are performed.
+unsafeModify :: (PrimMonad m, Unbox a) => MVector (PrimState m) a -> (a -> a) -> Int -> m ()
+{-# INLINE unsafeModify #-}
+unsafeModify = G.unsafeModify
+
+-- | Swap the elements at the given positions. No bounds checks are performed.
+unsafeSwap
+    :: (PrimMonad m, Unbox a) => MVector (PrimState m) a -> Int -> Int -> m ()
+{-# INLINE unsafeSwap #-}
+unsafeSwap = G.unsafeSwap
+
+-- Filling and copying
+-- -------------------
+
+-- | Set all elements of the vector to the given value.
+set :: (PrimMonad m, Unbox a) => MVector (PrimState m) a -> a -> m ()
+{-# INLINE set #-}
+set = G.set
+
+-- | Copy a vector. The two vectors must have the same length and may not
+-- overlap.
+copy :: (PrimMonad m, Unbox a)
+     => MVector (PrimState m) a   -- ^ target
+     -> MVector (PrimState m) a   -- ^ source
+     -> m ()
+{-# INLINE copy #-}
+copy = G.copy
+
+-- | Copy a vector. The two vectors must have the same length and may not
+-- overlap. This is not checked.
+unsafeCopy :: (PrimMonad m, Unbox a)
+           => MVector (PrimState m) a   -- ^ target
+           -> MVector (PrimState m) a   -- ^ source
+           -> m ()
+{-# INLINE unsafeCopy #-}
+unsafeCopy = G.unsafeCopy
+
+-- | Move the contents of a vector. The two vectors must have the same
+-- length.
+--
+-- If the vectors do not overlap, then this is equivalent to 'copy'.
+-- Otherwise, the copying is performed as if the source vector were
+-- copied to a temporary vector and then the temporary vector was copied
+-- to the target vector.
+move :: (PrimMonad m, Unbox a)
+                 => MVector (PrimState m) a -> MVector (PrimState m) a -> m ()
+{-# INLINE move #-}
+move = G.move
+
+-- | Move the contents of a vector. The two vectors must have the same
+-- length, but this is not checked.
+--
+-- If the vectors do not overlap, then this is equivalent to 'unsafeCopy'.
+-- Otherwise, the copying is performed as if the source vector were
+-- copied to a temporary vector and then the temporary vector was copied
+-- to the target vector.
+unsafeMove :: (PrimMonad m, Unbox a)
+                          => MVector (PrimState m) a   -- ^ target
+                          -> MVector (PrimState m) a   -- ^ source
+                          -> m ()
+{-# INLINE unsafeMove #-}
+unsafeMove = G.unsafeMove
+
+-- | Compute the next (lexicographically) permutation of given vector in-place.
+--   Returns False when input is the last permtuation
+nextPermutation :: (PrimMonad m,Ord e,Unbox e) => MVector (PrimState m) e -> m Bool
+{-# INLINE nextPermutation #-}
+nextPermutation = G.nextPermutation
+
+#define DEFINE_MUTABLE
+#include "unbox-tuple-instances"

third_party/bazel/rules_haskell/examples/vector/LICENSE

@@ -0,0 +1,30 @@
+Copyright (c) 2008-2012, Roman Leshchinskiy
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+- Redistributions of source code must retain the above copyright notice,
+this list of conditions and the following disclaimer.
+ 
+- Redistributions in binary form must reproduce the above copyright notice,
+this list of conditions and the following disclaimer in the documentation
+and/or other materials provided with the distribution.
+ 
+- Neither name of the University nor the names of its contributors may be
+used to endorse or promote products derived from this software without
+specific prior written permission. 
+
+THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY COURT OF THE UNIVERSITY OF
+GLASGOW AND THE CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
+INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+UNIVERSITY COURT OF THE UNIVERSITY OF GLASGOW OR THE CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
+DAMAGE.
+

third_party/bazel/rules_haskell/examples/vector/README.md

@@ -0,0 +1,6 @@
+The `vector` package [![Build Status](https://travis-ci.org/haskell/vector.png?branch=master)](https://travis-ci.org/haskell/vector)
+====================
+
+An efficient implementation of Int-indexed arrays (both mutable and immutable), with a powerful loop optimisation framework.
+
+See [`vector` on Hackage](http://hackage.haskell.org/package/vector) for more information.

third_party/bazel/rules_haskell/examples/vector/Setup.hs

@@ -0,0 +1,3 @@
+import Distribution.Simple
+main = defaultMain
+

third_party/bazel/rules_haskell/examples/vector/benchmarks/Algo/AwShCC.hs

@@ -0,0 +1,38 @@
+{-# OPTIONS -fno-spec-constr-count #-}
+module Algo.AwShCC (awshcc) where
+
+import Data.Vector.Unboxed as V
+
+awshcc :: (Int, Vector Int, Vector Int) -> Vector Int
+{-# NOINLINE awshcc #-}
+awshcc (n, es1, es2) = concomp ds es1' es2'
+    where
+      ds = V.enumFromTo 0 (n-1) V.++ V.enumFromTo 0 (n-1)
+      es1' = es1 V.++ es2
+      es2' = es2 V.++ es1
+
+      starCheck ds = V.backpermute st' gs
+        where
+          gs  = V.backpermute ds ds
+          st  = V.zipWith (==) ds gs
+          st' = V.update st . V.filter (not . snd)
+                            $ V.zip gs st
+
+      concomp ds es1 es2
+        | V.and (starCheck ds'') = ds''
+        | otherwise              = concomp (V.backpermute ds'' ds'') es1 es2
+        where
+          ds'  = V.update ds
+               . V.map (\(di, dj, gi) -> (di, dj))
+               . V.filter (\(di, dj, gi) -> gi == di && di > dj)
+               $ V.zip3 (V.backpermute ds es1)
+                        (V.backpermute ds es2)
+                        (V.backpermute ds (V.backpermute ds es1))
+
+          ds'' = V.update ds'
+               . V.map (\(di, dj, st) -> (di, dj))
+               . V.filter (\(di, dj, st) -> st && di /= dj)
+               $ V.zip3 (V.backpermute ds' es1)
+                        (V.backpermute ds' es2)
+                        (V.backpermute (starCheck ds') es1)
+

third_party/bazel/rules_haskell/examples/vector/benchmarks/Algo/HybCC.hs

@@ -0,0 +1,42 @@
+module Algo.HybCC (hybcc) where
+
+import Data.Vector.Unboxed as V
+
+hybcc :: (Int, Vector Int, Vector Int) -> Vector Int
+{-# NOINLINE hybcc #-}
+hybcc (n, e1, e2) = concomp (V.zip e1 e2) n
+    where
+      concomp es n
+        | V.null es = V.enumFromTo 0 (n-1)
+        | otherwise = V.backpermute ins ins
+        where
+          p = shortcut_all
+            $ V.update (V.enumFromTo 0 (n-1)) es
+
+          (es',i) = compress p es
+          r = concomp es' (V.length i)
+          ins = V.update_ p i
+              $ V.backpermute i r
+
+      enumerate bs = V.prescanl' (+) 0 $ V.map (\b -> if b then 1 else 0) bs
+
+      pack_index bs = V.map fst
+                    . V.filter snd
+                    $ V.zip (V.enumFromTo 0 (V.length bs - 1)) bs
+
+      shortcut_all p | p == pp   = pp
+                     | otherwise = shortcut_all pp
+        where
+          pp = V.backpermute p p
+
+      compress p es = (new_es, pack_index roots)
+        where
+          (e1,e2) = V.unzip es
+          es' = V.map (\(x,y) -> if x > y then (y,x) else (x,y))
+              . V.filter (\(x,y) -> x /= y)
+              $ V.zip (V.backpermute p e1) (V.backpermute p e2)
+
+          roots = V.zipWith (==) p (V.enumFromTo 0 (V.length p - 1))
+          labels = enumerate roots
+          (e1',e2') = V.unzip es'
+          new_es = V.zip (V.backpermute labels e1') (V.backpermute labels e2')

third_party/bazel/rules_haskell/examples/vector/benchmarks/Algo/Leaffix.hs

@@ -0,0 +1,16 @@
+module Algo.Leaffix where
+
+import Data.Vector.Unboxed as V
+
+leaffix :: (Vector Int, Vector Int) -> Vector Int
+{-# NOINLINE leaffix #-}
+leaffix (ls,rs)
+    = leaffix (V.replicate (V.length ls) 1) ls rs
+    where
+      leaffix xs ls rs
+        = let zs   = V.replicate (V.length ls * 2) 0
+              vs   = V.update_ zs ls xs
+              sums = V.prescanl' (+) 0 vs
+          in
+          V.zipWith (-) (V.backpermute sums ls) (V.backpermute sums rs)
+

third_party/bazel/rules_haskell/examples/vector/benchmarks/Algo/ListRank.hs

@@ -0,0 +1,21 @@
+module Algo.ListRank
+where
+
+import Data.Vector.Unboxed as V
+
+listRank :: Int -> Vector Int
+{-# NOINLINE listRank #-}
+listRank n = pointer_jump xs val
+  where
+    xs = 0 `V.cons` V.enumFromTo 0 (n-2)
+
+    val = V.zipWith (\i j -> if i == j then 0 else 1)
+                    xs (V.enumFromTo 0 (n-1))
+
+    pointer_jump pt val
+      | npt == pt = val
+      | otherwise = pointer_jump npt nval
+      where
+        npt  = V.backpermute pt pt
+        nval = V.zipWith (+) val (V.backpermute val pt)
+

third_party/bazel/rules_haskell/examples/vector/benchmarks/Algo/Quickhull.hs

@@ -0,0 +1,32 @@
+module Algo.Quickhull (quickhull) where
+
+import Data.Vector.Unboxed as V
+
+quickhull :: (Vector Double, Vector Double) -> (Vector Double, Vector Double)
+{-# NOINLINE quickhull #-}
+quickhull (xs, ys) = xs' `seq` ys' `seq` (xs',ys')
+    where
+      (xs',ys') = V.unzip
+                $ hsplit points pmin pmax V.++ hsplit points pmax pmin
+
+      imin = V.minIndex xs
+      imax = V.maxIndex xs
+
+      points = V.zip xs ys
+      pmin   = points V.! imin
+      pmax   = points V.! imax
+
+
+      hsplit points p1 p2
+        | V.length packed < 2 = p1 `V.cons` packed
+        | otherwise = hsplit packed p1 pm V.++ hsplit packed pm p2
+        where
+          cs     = V.map (\p -> cross p p1 p2) points
+          packed = V.map fst
+                 $ V.filter (\t -> snd t > 0)
+                 $ V.zip points cs
+
+          pm     = points V.! V.maxIndex cs
+
+      cross (x,y) (x1,y1) (x2,y2) = (x1-x)*(y2-y) - (y1-y)*(x2-x)
+