Main.hs

class FunctorIO f where
    fmapIO :: f a -> IO (f b)

data Input = Input Time Random Keyboard Mouse Joystick
data State = State {shizzle}
data Output = Output

data Game a = Game State a

instance FunctorIO Game where
    fmapIO :: Game (Maybe Input) -> IO (Game Output)
    fmapIO (Game state input) = do
        newState <- updateGame state input
        return $ Game newState Output

main :: IO ()
main = loop $ Game initialState Nothing
    where
        loop (Game state _) = do
            maybeInput <- getInput
            newGame <- fmapIO $ Game state maybeInput
            loop newGame