“…"的语义指的是“…"的语义. F#中的运算符 [英] Semantics of ">>" operator in F#

问题描述

在Microsoft的 F#示例中，他们使用">>"运算符作为如下:

In Microsoft's F# samples, they use the ">>" operator as follows:

test |> Seq.iter (any_to_string >> printfn "line %s");

在这种情况下，">>"运算符是做什么的?序列的每个项目(在这种情况下为数组)是否隐式传递给any_to_string?这与(fun item -> printfn "line %A" item)相似吗?

What does the ">>" operator do in this context? Is each item of the sequence (an array in this case) get passed to any_to_string implicitly? Is this similar to (fun item -> printfn "line %A" item)?

推荐答案

可以通过以下方式编写等效的代码:

An equivalent piece of code could be written the following way:

test |> Seq.iter(fun x -> printfn "line %s" (any_to_string x))

换句话说，>>运算符只是这样做:给定函数f(x)返回类型T和g(y)，且y的类型为T，则可以使用f >> g创建函数h( z)等于g(f(x)).除了内部和外部函数外，无需传递任何参数，结果是可以在您的代码中随时应用的函数，因此您可以执行以下操作:

In other words, the >> operator simply does this: given a function f(x) returning type T and g(y) with y being of type T, you can use f >> g to create a function h(z) being equivalent to g(f(x)). No argument but the inner and outer function has to be passed to that operator and the result is a function which can be applied at any time in your code, so you could do this:

//myFunc accepts any object, calls its ToString method, passes ToString
//result to the lambda which returns the string length. no argument is
//specified in advance
let myFunc = any_to_string >> (fun s -> s.Length)
let test = 12345
let f = 12345.0
//now we can call myFunc just like if we had definied it this way:
//let myFunc (x:obj) = obj.ToString().Length
printfn "%i" (myFunc i)
printfn "%i" (myFunc f)

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