F#让我这样做吗? [英] Does F# let me do this:

问题描述

我想编写一个带有参数'data'的函数.

I want to write a function that takes an argument 'data'.

我希望函数具有match语句，其中某些匹配项返回一个列表，而其他匹配项返回一个列表的元组-我认为这是不可能的，我也不能返回一个列表的元组或两个列表的元组-函数只能返回一种类型， 是吗?

I want the function to have a match statement where some matches return a list but others return a tuple of lists - I'm thinking this isn't possible nor can I return a tuple of one list or a tuple of two lists - a function can return only one kind of type, yes?

相关的问题-我可以编写一个F#函数来接受一个 单个列表或两个 列表的元组，并且在函数内部使用匹配项来查看实际上传递了哪些?

The related question also - can I write an F# function that can accept either a single list or a tuple of two lists and inside the function use a match to see which of these was actually passed?

K

推荐答案

您可以创建一个有区别的联合，其中一个案例包含一个列表，另一个案例包含两个列表的元组，并且然后返回.遵循这些原则...

You can create a discriminated union where one case holds a single list, and the other case holds a tuple of two lists, and then return that. Something along these lines...

type OneOrTwoLists<'a> =
    | OneList of 'a list
    | TwoLists of 'a list * 'a list

let producingFn () =
    if ... then
       OneList(listA)
    else
       TwoLists(listA, listB)

let consumingFn lists =
    match lists with
    | OneList theList ->
        // do something with it
    | TwoLists(listA, listB) ->
        // do something with them

这篇关于F#让我这样做吗?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！