接受用户输入直到井字游戏结束

Question

所以我通过CIS194 大约有八周的时间，我正在用 Haskell 制作一个超级简单的井字游戏。我已经把大部分游戏逻辑都搞定了，但我对用户输入部分感到困惑。

到目前为止，只是为了检查所有内容，我有一个糟糕的系统来硬编码用户和计算机的动作。

putStrLn "Welcome to tic tac toe. Where do you want to move first?"

let board1 = emptyBoard
putStrLn (show board1)
loc1 <- getLine
let moveLoc1 = read loc1
let board2 = findAndReplace board1 (Left moveLoc1) (Right O)

...

let board7 = makeXMove board6
putStrLn (show board7)
loc4 <- getLine
let moveLoc4 = read loc4
let board8 = findAndReplace board7 (Left moveLoc4) (Right O)


putStrLn (show board8)

不过，我的目标是接受用户输入，检查游戏是否结束，让计算机移动，检查游戏是否结束，如果没有则重复。在命令式语言中，我会在 while 循环中包装这样的内容，但我不确定如何在 Haskell 中解决这个问题。

从我在网上看到的情况来看，有很多东西听起来可能会有所帮助，但我不知道从哪里开始。例如，我也在看this example，我听说过很多关于Monads 和State 的信息，但是有没有什么介绍性的文献可以让我了解整个事情？

我目前所有的代码都可以在on github找到。

基本上我的问题是如何在游戏结束之前询问用户输入，并在游戏结束时停止询问他们？

Answer 1

你将棋盘传递给递归调用

player :: Board -> IO ()
player board1 = do
    putStrLn (show board1)
    loc1 <- getLine
    let moveLoc1 = read loc1
    let board2 = findAndReplace board1 (Left moveLoc1) (Right O)
    if over board2                    -- check to see if the game is over and we should stop recursing
    then putStrLn (outcome board2)    -- what to do when the game is over
    else computer board2              -- recurse for the other player if the game isn't over
--       |        ^-- the state of the board being passed to the recursive call
--       ^----------- the recursive call to the other player


computer :: Board -> IO ()
computer board1 = do
    let board2 = makeXMove board1
    if over board2                    -- check to see if the game is over and we should stop recursing
    then putStrLn (outcome board2)    -- what to do when the game is over
    else player board2                -- recurse for the other player if the game isn't over
--       |        ^-- the state of the board being passed to the recursive call
--       ^----------- the recursive call to the other player

您需要填写检测游戏何时结束的函数over :: Board -> Bool 和描述游戏结果的outcome :: Board -> String。你会在玩家开始游戏时先用

main = do
    putStrLn "Welcome to tic tac toe. Where do you want to move first?"
    player emptyBoard

player 和 computer 中有很多代码重复。对自己来说，一个很好的挑战是弄清楚如何摆脱重复的代码。你能改变player，让它不知道computer，反之亦然，然后让两个player互相对战（可能稍微修改一下，以区分哪个是X，哪个是O )?