是“可选"的管道操作员惯用的F# [英] is an "optionalized" pipe operator idiomatic F#

问题描述

我很喜欢使用管道运算符'|>'.但是，当将返回简单"值的函数与返回"Option-Typed-values"的函数混合时，情况会变得有些混乱，例如:

I like to use the pipe operator '|>' a lot. However, when mixing functions that return 'simple' values with functions that return 'Option-Typed-values', things become a bit messy e.g.:

// foo: int -> int*int
// bar: int*int -> bool
let f (x: string) = x |> int |> foo |> bar

可行，但可能会抛出'System.FormatException:...'

works, but it might throw a 'System.FormatException:...'

现在假设我想通过使函数'int'提供可选结果来解决此问题:

Now assume I want to fix that by making the function 'int' give an optional result:

let intOption x = 
    match System.Int32.TryParse x with
    | (true, x) -> Some x
    | (false,_) -> None

现在唯一的问题就是函数

Only problem now is that of course the function

let g x = x |> intOption |> foo |> bar

由于输入错误而无法编译.好的，只需定义一个可选"管道:

won't compile due to typing errors. Ok, simply define an 'optionalized' pipe:

let ( |= ) x f = 
   match x with
   | Some y -> Some (f y)
   | None -> None

现在我可以简单地定义:

now I can simply define:

let f x = x |> intOption |= foo |= bar

一切都像个魔术.

好，问题:那是惯用的F#吗?可以接受吗风格不好?

备注:当然，给定正确的类型，'| ='运算符允许随意拆分和合并带有选项的管道"，而仅在意重要的选项:

Remark: Of course, given the right types the '|=' operator allows to split and merge 'pipelines' with options at will while only care about options where they matter:

x |> ...|> divisionOption |= (fun y -> y*y) |=...|>...

推荐答案

我认为使用Option.map会更惯用:

I think using Option.map would be more idiomatic:

让g x = x |> intOption |> Option.map foo |> Option.map栏

let g x = x |> intOption |> Option.map foo |> Option.map bar

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