sdl.hs

import Data.Bits
import Data.Word
import Data.IORef
import qualified Graphics.UI.SDL as SDL 
import qualified Graphics.UI.SDL.Primitives as SDL 

main = do
  SDL.init [SDL.InitEverything]
  SDL.setVideoMode 640 480 32 []
  var <- newIORef (0, 0)
  let loop = do
    event <- SDL.pollEvent
    case event of
      (SDL.KeyDown SDL.SDLK_DOWN) -> modifyIORef var (\(x, y) -> (x, y-1))
      (SDL.KeyDown SDL.SDLK_UP)   -> modifyIORef var (\(x, y) -> (x, y+1))
      (SDL.KeyDown SDL.SDLK_LEFT) -> modifyIORef var (\(x, y) -> (x-1, y)) 
      (SDL.KeyDown SDL.SDLK_RIGHT -> modifyIORef var (\(x, y) -> (x+1, y)) 
      _ -> return ()
    fmap renderBox var 
  loop


renderBox :: (Int, Int) -> IO ()
renderBox (x, y) = do
  SDL.box screen (SDL.Rect x y 100 100) $ rgbColor 255 255 255 
  SDL.flip screen

rgbColor :: Word8 -> Word8 -> Word8 -> SDL.Pixel
rgbColor r g b = SDL.Pixel (shiftL (fi r) 24 .|. 
                            shiftL (fi g) 16 .|. 
                            shiftL (fi b) 8  .|. 
                            255)
  where fi = fromIntegral

foo.hs:12:5: parse error on input `event'