Question

我正在学习人工智能课程的球拍。对于第一个项目，老师给了我们一个包含合同和单元测试的文件，我们将编写使其运行所需的功能。我刚刚创建了我需要的函数的存根，并且除了一个之外还满足了所有的合同：

[start-state (and/c state? (not/c state-game-over?))]

我声明的功能目前看起来像这样：

(define (start-state)
  (state '() start-tiles 0)
)

状态结构由老师给出：

(struct state (played unplayed passes) #:prefab)

合同：

[struct state ((played (listof (and/c tile? tile-at-origin?)))
             (unplayed (listof (and/c tile? tile-on-board?)))
             (passes pass-count?))]

崩溃时出现错误：

start-state: broke its contract
promised: (and/c state? (not/c state-game-over?))
produced: #<procedure:start-state>
which isn't: state?
in: (and/c state? (not/c state-game-over?))
contract from:

我相信我的start-state过程会创建并返回一个状态结构，但显然它会自行返回并违反合同。如何返回结构而不是程序？

Answer 1

看起来start-state不应该是一个过程，而是一个值。也就是说，你需要做

(define start-state (start ...))

而不是

(define (start-state) ...)

球拍合同和结构问题

1 个答案: