Buffer events with playMSF

src/Game/Utils.hs

@@ -10,10 +10,10 @@ import Graphics.Gloss.Interface.IO.Game
 
 -- | Display an MSF outputting a picture value as a window using Gloss.
 -- Note that the MSF is not passed a real-time clock.
-playMSF :: Display -> Color -> Int -> MSF IO (Maybe Event) Picture -> IO ()
+playMSF :: Display -> Color -> Int -> MSF IO [Event] Picture -> IO ()
 playMSF display color freq msf = do
   -- `react` doesn't allow inputs or outputs, so we have to use IORefs
-  evRef <- newIORef Nothing
+  evRef <- newIORef []
   picRef <- newIORef blank
 
   handle <- reactInit (constM (readIORef evRef) >>> msf >>> arrM (writeIORef picRef))
@@ -23,21 +23,21 @@ playMSF display color freq msf = do
 
       -- A function to handle input events.
       handleInput e _ = do
-        writeIORef evRef (Just e)
+        modifyIORef evRef (e :)
 
       -- A function to step the world one iteration.
       stepWorld _ _ = do
         react handle
-        writeIORef evRef Nothing
+        writeIORef evRef []
 
   playIO display color freq () toPic handleInput stepWorld
 
 -- * DrawerT
 
-type DrawerT m = WriterT Picture (Control.Monad.Trans.MSF.Reader.ReaderT (Maybe Event) m)
+type DrawerT m = WriterT Picture (ReaderT [Event] m)
 
-runDrawerS :: Monad m => MSF (DrawerT m) () () -> MSF m (Maybe Event) Picture
+runDrawerS :: Monad m => MSF (DrawerT m) () () -> MSF m [Event] Picture
-runDrawerS msf = arr (,()) >>> Control.Monad.Trans.MSF.Reader.runReaderS (runWriterS msf) >>> arr fst
+runDrawerS msf = arr (,()) >>> runReaderS (runWriterS msf) >>> arr fst
 
 draw :: Monad m => MSF (DrawerT m) Picture ()
 draw = arrM tell