Add 'users/glittershark/xanthous/' from commit '53b56744f4'

git-subtree-dir: users/glittershark/xanthous
git-subtree-mainline: 91f53f02d8
git-subtree-split: 53b56744f4

users/glittershark/xanthous/src/Xanthous/App/Common.hs

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+--------------------------------------------------------------------------------
+module Xanthous.App.Common
+  ( describeEntities
+  , describeEntitiesAt
+  , entitiesAtPositionWithType
+
+    -- * Re-exports
+  , MonadState
+  , MonadRandom
+  , EntityMap
+  , module Xanthous.Game.Lenses
+  , module Xanthous.Monad
+  ) where
+--------------------------------------------------------------------------------
+import           Xanthous.Prelude
+--------------------------------------------------------------------------------
+import           Data.Aeson (object)
+import qualified Data.Aeson as A
+import           Control.Monad.State (MonadState)
+import           Control.Monad.Random (MonadRandom)
+--------------------------------------------------------------------------------
+import           Xanthous.Data (Position, positioned)
+import           Xanthous.Data.EntityMap (EntityMap)
+import qualified Xanthous.Data.EntityMap as EntityMap
+import           Xanthous.Game
+import           Xanthous.Game.Lenses
+import           Xanthous.Game.State
+import           Xanthous.Monad
+import           Xanthous.Entities.Character (Character)
+import           Xanthous.Util.Inflection (toSentence)
+--------------------------------------------------------------------------------
+
+entitiesAtPositionWithType
+  :: forall a. (Entity a, Typeable a)
+  => Position
+  -> EntityMap SomeEntity
+  -> [(EntityMap.EntityID, a)]
+entitiesAtPositionWithType pos em =
+  let someEnts = EntityMap.atPositionWithIDs pos em
+  in flip foldMap someEnts $ \(eid, view positioned -> se) ->
+    case downcastEntity @a se of
+      Just e  -> [(eid, e)]
+      Nothing -> []
+
+describeEntitiesAt :: (MonadState GameState m, MonadRandom m) => Position -> m ()
+describeEntitiesAt pos =
+  use ( entities
+      . EntityMap.atPosition pos
+      . to (filter (not . entityIs @Character))
+      ) >>= \case
+        Empty -> pure ()
+        ents  -> describeEntities ents
+
+describeEntities
+  :: ( Entity entity
+    , MonadRandom m
+    , MonadState GameState m
+    , MonoFoldable (f Text)
+    , Functor f
+    , Element (f Text) ~ Text
+    )
+  => f entity
+  -> m ()
+describeEntities ents =
+  let descriptions = description <$> ents
+  in say ["entities", "description"]
+     $ object ["entityDescriptions" A..= toSentence descriptions]