Why sort([1,2,3]){true} doesn't work in Swift?

Question

我知道这个例子是完全没有用的和人为的，但是我试图更好地围绕Swift中的值处理方式，我不明白为什么下面的代码会返回错误。

var notSorted = sort([1,2,3,4]){true}

Answer 1

The second parameter of sort has type (T, T) -> Bool , but you are supplying a () -> Bool , namely a closure with no parameters that returns true .

Of course the two types don't match and you rightfully get a compile-time error.

Something like this will work:

var notSorted = sort([1,2,3,4]){_ in true}

---

By the way, that closure has the effect of reversing the array. If you want to perform a nop, you have to put false .