未能與實際類型'（控制器 - > IO（）） - > IO（）'預期類型'IO（）'

Question

我是Haskell的新手，當我嘗試配置我碼。我明白main（）中的所有指令都需要是IO（），並且發生錯誤是因爲我使用的函數之一（在Graphics.Gloss.Interface.IO.Animate中）沒有返回IO（）。我想用光澤包顯示遺傳算法的結果。 這裏是我的代碼：

module Main where 

import Prelude as P 
import Control.Monad.Random as Rand 
import Data.Functor 
import Data.IORef 
import Graphics.Gloss.Interface.IO.Animate 
import Graphics.Solution 
import Graphics.Plot 

import Args 
import Task 
import Parsing 
import Genetic 

import Control.Concurrent.Async 
import Control.Concurrent.STM.TChan 
import Control.Monad.STM 
import Control.Arrow (first) 


main :: IO() 
main = do 
    args <- parseOptions 

    opts <- loadEvolOptions (evolOptionsFileName args) 
    gen <- newStdGen 
    task@(Task _ twrs _ _) <- loadTask (inputFileName args) (fitnessFuncFileName args) 

    chan <- newTChanIO 
    asolution <- async $ solve chan gen opts task 
    dataRef <- newIORef [] 
    finalSolutionRef <- newIORef Nothing 

    animateIO mode white $ const $ do 
     mfinsol <- readIORef finalSolutionRef 
     case mfinsol of 
     Just solution -> do 
      samples <- readIORef dataRef 
      return $ solutionPicture task solution (fitnessPlot samples) 
     Nothing -> do 
      msolution <- poll asolution  
      case msolution of 
      Nothing -> do 
       mv <- atomically $ tryReadTChan chan 
       case mv of 
       Nothing -> return() 
       Just v -> modifyIORef dataRef (++[v]) 
       samples <- readIORef dataRef 
       return $ fitnessPlot samples 
      Just esol -> case esol of 
       Left e -> fail $ show e 
       Right solution -> do 
       saveResult (outputFileName args) (filterTowers solution twrs) 
       writeIORef finalSolutionRef (Just solution) 
       samples <- readIORef dataRef 
       return $ solutionPicture task solution (fitnessPlot samples) 
     where mode = InWindow "test_genetic_al" (1280, 1024) (10, 10) 
      fitnessPlot ds = translate (-300) (-200) $ scale 600 600 $ plot "generation" "fitness" $ first fromIntegral <$> ds 

這是我的了：

Couldn't match expected type ‘IO()’ 
       with actual type ‘(Controller -> IO()) -> IO()’ 
    In a stmt of a 'do' block: 
     animateIO mode white 
     $ const 
     $ do { mfinsol <- readIORef finalSolutionRef; 
       case mfinsol of { 
       Just solution -> do { ... } 
       Nothing -> do { ... } } } 
    In the expression: 
     do { args <- parseOptions; 
      opts <- loadEvolOptions (evolOptionsFileName args); 
      gen <- newStdGen; 
      task@(Task _ twrs _ _) <- loadTask 
             (inputFileName args) (fitnessFuncFileName args); 
      .... } 
    In an equation for ‘main’: 
     main 
      = do { args <- parseOptions; 
       opts <- loadEvolOptions (evolOptionsFileName args); 
       gen <- newStdGen; 
       .... } 
      where 
       mode = InWindow "test_genetic_al" (1280, 1024) (10, 10) 
       fitnessPlot ds 
       = translate (- 300) (- 200) 
        $ scale 600 600 
        $ plot "generation" "fitness" $ first fromIntegral <$> ds 

我已經在谷歌搜索我的問題和StackOverflow上了這麼多次，但仍然無法找到一個解決方案錯誤。請幫幫我。

P/S：這是Graphics.Gloss引導線：https://hackage.haskell.org/package/gloss-1.11.1.1/docs/Graphics-Gloss-Interface-IO-Animate.html

爲我愚蠢的問題再次對不起，以後我給Lazersmoke的建議（你可以在評論區見下文），我得到了另一個錯誤與我要求的錯誤非常類似：

我改了行：animateIO模式白色$常量$千萬

分爲：animateIO模式白（_ - >收益率（））$常量$做

Couldn't match type ‘Picture’ with ‘()’ 
    Expected type: Controller -> IO() 
     Actual type: Controller -> IO Picture 
    In the second argument of ‘($)’, namely 
     ‘const 
     $ do { mfinsol <- readIORef finalSolutionRef; 
       case mfinsol of { 
       Just solution -> do { ... } 
       Nothing -> do { ... } } }’ 
    In a stmt of a 'do' block: 
     animateIO mode white (\ _ -> return()) 
     $ const 
     $ do { mfinsol <- readIORef finalSolutionRef; 
       case mfinsol of { 
       Just solution -> do { ... } 
       Nothing -> do { ... } } } 
    In the expression: 
     do { args <- parseOptions; 
      opts <- loadEvolOptions (evolOptionsFileName args); 
      gen <- newStdGen; 
      task@(Task _ twrs _ _) <- loadTask 
             (inputFileName args) (fitnessFuncFileName args); 
      .... } 

Answer 1

animateIO需要多少個參數？

animateIO :: Display  
      -> Color 
      -> (Float -> IO Picture) 
      -> (Controller -> IO()) 
      -> IO() 

四。你提供了多少個參數給animateIO？

animateIO mode white $ … 

三。該類型的

animateIO mode white $ … 

是(Controller -> IO()) -> IO()，這正是你的錯誤信息告訴你。既然你不想使用Controller -> IO()一部分，你可以提供自己的animateIO：

animateIO' :: Display -> Color -> IO Picture -> IO() 
animateIO' m c a = animateIO m c (const a) (const $ return()) 

請注意，您的(\_ -> return())沒有工作，因爲第三個參數具有生產Picture，而不是一個IO()。