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我測試了簡單的乒乓球比賽在這裏找到：https://github.com/shangaslammi/frp-pongGLUT鍵盤奇慢無比
的問題是，該鍵盤控制工作非常糟糕 - 鍵是奇慢無比，經常有幾秒鐘的延遲。我假設作者爲Windows編寫代碼是因爲他包含了一個.bat文件，所以這是一個特定於Linux的問題。
這是怎麼發生的？
我不確定是哪裏的問題會是，但這裏是文件Keyboard.hs：
import Data.Set (Set)
import qualified Data.Set as Set
import Graphics.UI.GLUT (Key(..), KeyState(..))
-- | Set of all keys that are currently held down
newtype Keyboard = Keyboard (Set Key)
-- | Create a new Keyboard
initKeyboard :: Keyboard
initKeyboard = Keyboard Set.empty
-- | Record a key state change in the given Keyboard
handleKeyEvent :: Key -> KeyState -> Keyboard -> Keyboard
handleKeyEvent k Down = addKey k
handleKeyEvent k Up = removeKey k
addKey :: Key -> Keyboard -> Keyboard
addKey k (Keyboard s) = Keyboard $ Set.insert k s
removeKey :: Key -> Keyboard -> Keyboard
removeKey k (Keyboard s) = Keyboard $ Set.delete k s
-- | Test if a key is currently held down in the given Keyboard
isKeyDown :: Keyboard -> Key -> Bool
isKeyDown (Keyboard s) k = Set.member k s
，並設置回調：
type KeyboardRef = IORef Keyboard
type TimeRef = IORef POSIXTime
type AccumRef = TimeRef
type PrevTimeRef = TimeRef
type GameRef = IORef (Rects, GameLogic)
type CallbackRefs = (AccumRef, PrevTimeRef, KeyboardRef, GameRef)
initCallbackRefs :: IO CallbackRefs
initCallbackRefs = do
accum <- newIORef secPerTick
prev <- getPOSIXTime >>= newIORef
keyb <- newIORef initKeyboard
cont <- newIORef ([],game)
return (accum, prev, keyb, cont)
-- | Update the Keyboard state according to the event
handleKeyboard :: CallbackRefs -> KeyboardMouseCallback
handleKeyboard (_, _, kb, _) k ks _ _ = modifyIORef kb (handleKeyEvent k ks)