我在计划中构建一个Nim游戏，提示用户输入桩号和他们想要删除的物品数量。计算机将简单地从第一堆中移除1，如果第一堆是空的，它将从第二堆中移除，而不是第三堆。
我的代码无法正常运行，有人可以指出我犯错误的地方吗？提前谢谢。
这是我的代码：
(define play-with-turns
(lambda (game-state player)
(display-game-state game-state)
(cond ((over? game-state)
(announce-winner player))
((equal? player 'human)
(play-with-turns (human-move game-state) 'computer))
((equal? player 'computer)
(play-with-turns (computer-move game-state) 'human))
(else
(error "player wasn't human or computer:" player)))))
(define computer-move
(lambda (game-state)
(let ((pile (if (> (size-of-pile game-state 1) 0)
1
2)))
(display "I take 1 coin from pile ")
(display pile)
(newline)
(remove-coins-from-pile game-state 1 pile))))
(define prompt
(lambda (prompt-string)
(newline)
(display prompt-string)
(newline)
(read)))
(define human-move
(lambda (game-state)
(let ((p (prompt "Which pile will you remove from?")))
(let ((n (prompt "How many coins do you want to remove?")))
(remove-coins-from-pile game-state n p)))))
(define over?
(lambda (game-state)
(= (total-size game-state) 0)))
(define announce-winner
(lambda (player)
(if (equal? player 'human)
(display "You lose. Better luck next time.")
(display "You win. Congratulations."))))
(define remove-coins-from-pile
(lambda (game-state num-coins pile-number)
(cond ((= pile-number 1)
(make-game-state (- (size-of-pile game-state 1)
num-coins)
(size-of-pile game-state 2)
(size-of-pile game-state 3)))
((= pile-number 2)
(make-game-state (size-of-pile game-state 1)
(- (size-of-pile game-state 2)
num-coins)
(size-of-pile game-state 3)))
((= pile-number 3)
(make-game-state (size-of-pile game-state 1)
(size-of-pile game-state 2)
(- (size-of-pile game-state 3)
num-coins))))))
(define exponent-of-in
(lambda (n int)
(if (= (remainder int n) 0)
(+ 1 (exponent-of-in n (quotient int n)))
0)))
(define make-game-state
;Returns a game state with n coins in the first pile
;m coins in the second pile, and k coins in the third pile.
(lambda (n m k)
(lambda (x)
(cond ((= x 1) n)
((= x 2) m)
((= x 3) k)))))
(define size-of-pile
;Returns an integer equal to the number of coins in
;pile pile-number of the game-state.
(lambda (game-state pile-number)
(game-state pile-number)))
;; Utilities
(define display-game-state
(lambda (game-state)
(newline)
(newline)
(display " Pile 1: ")
(display (size-of-pile game-state 1))
(newline)
(display " Pile 2: ")
(display (size-of-pile game-state 2))
(newline)
(display " Pile 3: ")
(display (size-of-pile game-state 3))
(newline)
(newline)))
(define total-size
(lambda (game-state)
(+(+ (size-of-pile game-state 1)
(size-of-pile game-state 2)) (size-of-pile game-state 3))))
示例输出：
(play-with-turns (make-game-state 5 9 8) 'human)
Pile 1: 5
Pile 2: 9
Pile 3: 8
Which pile will you remove from?
1
How many coins do you want to remove?
2
Pile 1: 4
Pile 2: 9
Pile 3: 8
I take 1 coin from pile 1
Pile 1: 3
Pile 2: 9
Pile 3: 8
Which pile will you remove from?
2
How many coins do you want to remove?
2
Pile 1: 2
Pile 2: 7
Pile 3: 8
I take 1 coin from pile 1
Pile 1: 1
Pile 2: 7
Pile 3: 8
Which pile will you remove from?
2
How many coins do you want to remove?
2
Pile 1: 1
Pile 2: 5
Pile 3: 8
I take 1 coin from pile 1
Pile 1: 0
Pile 2: 5
Pile 3: 8
答案 0 :(得分：0)
首先要做的事情：我强烈建议您按照How To Design Programs中所述的设计方案进行操作。首先，您的函数可以真正使用每个单行目的语句。接下来，您真的需要这些功能的测试用例。我强烈怀疑你的remove-coins-from-pile函数有问题。
我看到您的代码中至少有一个错误，您可以通过一组好的测试用例轻松捕获这些错误。如果您正在使用其中一种学生语言，您应该能够通过写作来测试，例如：
(check-expect ((remove-coins-from-pile (make-game-state 3 9 7) 5 2) 3) 172)
请注意，此测试用例实际上是错误的;你必须解决它。
如果您使用完整的#lang球拍语言，则需要添加
(require rackunit)
然后使用check-equal进行测试？：
(check-equal? ((remove-coins-from-pile (make-game-state 3 9 7) 5 2) 3) 172)
老实说，有人引导你走向基于功能的方法（游戏状态被表示为一种功能），这使得测试比其他方式更加困难;如果你有一个“游戏状态”结构，你可以通过写作来测试整个游戏状态，例如，
(check-equal? (remove-coins-from-pile (make-game-state 3 9 7) 5 2)
(make-game-state 17 27 0))
我猜这是一个真正喜欢功能的教练的作业。嗯，说实话，我非常喜欢功能，但它们并不顺利 在这样的情况下进行测试。
有关详细信息，我会再次推荐您使用如何设计程序文本。