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

third_party/bazel/rules_haskell/tests/hidden-modules/BUILD.bazel

@@ -0,0 +1,35 @@
+load(
+    "@io_tweag_rules_haskell//haskell:haskell.bzl",
+    "haskell_library",
+)
+
+package(
+    default_testonly = 1,
+    default_visibility = ["//visibility:public"],
+)
+
+haskell_library(
+    name = "lib-a",
+    srcs = glob(["lib-a/*.hs"]),
+    hidden_modules = ["Foo"],
+    src_strip_prefix = "lib-a",
+    deps = ["//tests/hackage:base"],
+)
+
+haskell_library(
+    name = "lib-b",
+    srcs = glob(["lib-b/*.hs"]),
+    src_strip_prefix = "lib-b",
+    deps = ["//tests/hackage:base"],
+)
+
+haskell_library(
+    name = "lib-c",
+    srcs = glob(["lib-c/*.hs"]),
+    src_strip_prefix = "lib-c",
+    deps = [
+        ":lib-a",
+        ":lib-b",
+        "//tests/hackage:base",
+    ],
+)

third_party/bazel/rules_haskell/tests/hidden-modules/lib-a/Bar.hs

@@ -0,0 +1,6 @@
+module Bar (bar) where
+
+import Foo (foo)
+
+bar :: Int
+bar = foo * 2

third_party/bazel/rules_haskell/tests/hidden-modules/lib-a/Foo.hs

@@ -0,0 +1,4 @@
+module Foo (foo) where
+
+foo :: Int
+foo = 15

third_party/bazel/rules_haskell/tests/hidden-modules/lib-b/Foo.hs

@@ -0,0 +1,4 @@
+module Foo (foo) where
+
+foo :: Int
+foo = 16

third_party/bazel/rules_haskell/tests/hidden-modules/lib-c/Baz.hs

@@ -0,0 +1,7 @@
+module Baz (bar) where
+
+import Foo (foo)
+import Bar (bar)
+
+baz :: Int
+baz = foo + bar