Implement event handler

src/Game/Engine.hs

@@ -1,14 +1,34 @@
 {-# LANGUAGE Arrows #-}
+{-# LANGUAGE OverloadedRecordDot #-}
+{-# LANGUAGE RecordWildCards #-}
 
 module Game.Engine where
 
+import Control.Monad.Trans.MSF.Reader
+import Control.Monad.Trans.MSF.Writer
+import Data.Maybe
 import Data.MonadicStreamFunction
+import Game.Display
 import Game.State
 import Game.Utils
+import Graphics.Gloss
+import Graphics.Gloss.Interface.IO.Game
 
 handleEvents :: Monad m => MSF (DrawerT m) () [Direction]
-handleEvents = proc () -> do
-  returnA -< []
+handleEvents = mapMaybe getDir <$> liftTransS (constM ask)
+  where
+    getDir :: Event -> Maybe Direction
+    getDir (EventKey k Down _ _) = case k of
+      Char 'w' -> Just U
+      Char 's' -> Just D
+      Char 'a' -> Just L
+      Char 'd' -> Just R
+      SpecialKey KeyUp -> Just U
+      SpecialKey KeyDown -> Just D
+      SpecialKey KeyLeft -> Just L
+      SpecialKey KeyRight -> Just R
+      _ -> Nothing
+    getDir _ = Nothing
 
 tick :: Monad m => MSF (DrawerT m) (Maybe Direction) GameState
 tick = next initialState $ feedback initialState $ proc (dir, state) -> do