F＃中“ ==>”语法的含义

Question

考虑以下F＃代码

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

接着

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)

我不明白的是最后一行中的==> ！！！

它是什么？

Answer 1

==>运算符是FsCheck的一部分。 它用于表示仅在某些条件为true时才应保留的属性。

因此，在您的示例中：

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

这意味着仅当ordered xs为true时， ordered (insert x xs)应该为true。

您可以在FsCheck文档的“条件属性”部分中了解有关此内容的更多信息。