我如何在Haskell中编写游戏循环？ [英] How do I write a game loop in Haskell?

问题描述

我想在Haskell中编写一个游戏，每次迭代循环计算世界的状态。我认为我应该创建一个函数：

  gameLoop :: World  - >世界
  -  ... 
  

并有 main :: IO（）调用它：

  main = do 
 gameLoop  -  ... 
  

但问题在于我缺少一些基本的理解，如何将 gameLoop 函数，以便它返回 main 的参数值。

我们将在Haskell中创建一个游戏循环？

解决方案

您可能需要类似这样的内容

  import Control.Monad.Loops 
 $ b $ main = iterateM_ 
（\w  - > displayWorld w> > return（gameLoop w））
 initWorld 
  -  iterateM_（（>>）< $> displayWorld< return> gameLoop）initWorld 
  

或者，如果您不想使用整个monad-loops软件包（尽管它很有可能）

  main = loop initWorld 
其中loop w = disp layWorld w>>循环（gameLoop w）
  

基本上，你只是在绘制世界，然后再循环到下一个状态。

更有可能你想要这样的东西，但

   -  - 当用户想要退出游戏时出错
 KeepGoing :: World  - > Bool 
 
 main = iterateUntilM_ keepGoing displayLoop initWorld 
 where displayLoop w = displayWorld w>>返回（gameLoop w）
  

因为否则你不能停止：）

I want to code a game in Haskell where every iteration of the loop computes the state of the world. I thought I should create a function:

gameLoop :: World -> World
-- ...

and have main :: IO () call it:

main = do
    gameLoop -- ...

But the problem is that I'm missing some fundamental understanding of how to wrap the gameLoop function so that it returns main's parameter value.

How would one go about creating a game loop in Haskell?

解决方案

You'll probably want something like this

import Control.Monad.Loops

main = iterateM_ 
       (\w -> displayWorld w >> return (gameLoop w))
       initWorld
-- iterateM_ ((>>) <$> displayWorld <*> return . gameLoop) initWorld

Or if you don't want to use the whole monad-loops package (even though it rocks)

main = loop initWorld
  where loop w = displayWorld w >> loop (gameLoop w)

Basically you're just drawing the world, then looping again to with the next state.

More likely you want something like this though

 -- False when the user wants to exit the game
 keepGoing :: World -> Bool

 main = iterateUntilM_ keepGoing displayLoop initWorld
   where displayLoop w = displayWorld w >> return (gameLoop w)

Since otherwise you can't stop :)

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