F#中“==>”语法的含义

Question

考虑 F# 中的以下代码

let rec ordered xs = 
    match xs with
      | [] | [_]        -> true
      | x1 :: x2 :: xs'  -> x1 <= x2 && ordered (x2 :: xs')

然后

let rec insert x xs = 
    match xs with
    | []      -> [x]
    | y :: ys -> if x <= y then x :: y :: ys 
                 else           y :: insert x ys

最后

let insertKeepsOrder (x : int) xs = ordered xs ==> ordered (insert x xs)

最后一行的==>意思我看不懂！！！

这是什么？

Answer 1

==> 运算符是 FsCheck 的一部分。它用于表达一个属性应该保持 仅当某些条件为真时 .

所以在你的例子中：

let insertKeepsOrder (x : int) xs = ordered xs ==> ordered (insert x xs)

这意味着只有当 ordered xs 为真时 ordered (insert x xs) 才为真。

您可以在 the "Conditional Properties" section of the FsCheck documentation 中阅读更多相关信息。

F#中“==>”语法的含义

Meaning of "==>" syntax in F#

f#

fscheck