我正在尝试使用Haskell在SDL 2中绘制随机定位的矩形。IO monad真的让我抓狂，我无法让它工作。我已经准备好了SDL 2的样板代码和RectangleObject的自定义数据类型，我想做的就是在main函数中随机生成矩形，然后在appLoop函数中绘制它们。
我得到的错误：

BadRandomRectangles.hs:17:61-85: error:
    • Couldn't match expected type: [RectangleObject]
                  with actual type: IO [RectangleObject]
    • In the fourth argument of ‘GameState’, namely
        ‘(createRandomRectangles 10)’
      In the expression:
        GameState
          (V2 10 10) (V2 40 40) (V2 1 1) (createRandomRectangles 10)
      In an equation for ‘gameState’:
          gameState
            = GameState
                (V2 10 10) (V2 40 40) (V2 1 1) (createRandomRectangles 10)
   |
17 |   let gameState = GameState (V2 10 10) (V2 40 40) (V2 1 1) (createRandomRectangles 10) in
   |                                                             ^^^^^^^^^^^^^^^^^^^^^^^^^

字符串
我的代码是：

{-# LANGUAGE OverloadedStrings #-}

import SDL
import System.Random
import Control.Monad (unless, replicateM)
import Foreign.C.Types (CInt)

data RectangleObject = RectangleObject { rectPosn :: V2 CInt, rectDim :: V2 CInt };

data GameState = GameState { posn :: V2 CInt, dim :: V2 CInt, vel :: V2 CInt, objects :: [RectangleObject] };

main :: IO ()
main = do
  initializeAll
  window <- createWindow "Rectangles" (defaultWindow { windowInitialSize = V2 640 480 })
  renderer <- createRenderer window (-1) defaultRenderer
  let gameState = GameState (V2 10 10) (V2 40 40) (V2 1 1) (createRandomRectangles 10) in
    appLoop renderer gameState
  destroyRenderer renderer
  destroyWindow window
  quit

appLoop :: Renderer -> GameState -> IO ()
appLoop renderer gameState = do
  events <- pollEvents

  clear renderer
  rendererDrawColor renderer $= V4 0 0 0 255

  -- Get the RectangleObjects from the game state and draw them
  let objs = objects gameState
  mapM_ (\(RectangleObject posn dim) -> fillRect renderer (Just $ Rectangle (P $ posn) dim)) objs

  -- Fill a rectangle of size 1280x720 with black color
  fillRect renderer (Just $ Rectangle (P $ V2 0 0) (V2 1280 720))
  rendererDrawColor renderer $= V4 255 0 0 255

  fillRect renderer (Just $ Rectangle (P $ posn gameState) (dim gameState))
  present renderer
  SDL.delay 16
  unless qPressed (appLoop renderer (updateGameState vGameState))

updateGameState :: GameState -> GameState
updateGameState (GameState posn dim vel objs) =
  GameState (posn + vel) dim vel objs

createRandomRectangles :: Int -> IO [RectangleObject]
createRandomRectangles n = replicateM n generateRandomRectangle

generateRandomRectangle :: IO RectangleObject
generateRandomRectangle = do
  x <- randomRIO (1, 10)
  y <- randomRIO (1, 10)
  w <- randomRIO (1, 10)
  h <- randomRIO (1, 10)
  return $ RectangleObject (V2 x y) (V2 w h)

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