helm turtle 基于helm游戏引擎的海龟模块

舵龟基于helm游戏引擎的Turtle模块。例子import FRP.Helm import FRP.Helm.Window as Window import FRP.Helm.Turtle myprogram :: FieldAction myprogram = do setSpeed 20 penUp goto (( - 200 ), 0 ) penDown koch 500 koch :: Int -> FieldAction koch n | n <= 10 = fd 5 | otherwise = do koch (n `div` 3 ) lt 60 koch (n `div` 3 ) rt 120 koch (n `div` 3