合并两个列表 [英] Merge two lists

问题描述

我希望以纯函数方式在 F# 中合并 2 个列表.我很难理解语法.

I am looking to merge 2 lists in F# in a purely functional way. I am having a hard time understanding the syntax.

假设我有一个元组 ([5;3;8],[2;9;4])

当我调用函数时，它应该返回[5;2;3;9;8;4]

When I call the function, it should return [5;2;3;9;8;4]

这就是我到目前为止的原因，我敢肯定这是错误的.如果有人能以简单的方式解释它，我将不胜感激.

Here is why I have so far, which is wrong I am sure. If someone could explain it in a simple way I would be grateful.

let rec interleave (xs,ys) = function
|([], ys) -> ys
|(x::xs, y::ys) -> x :: y::  interleave (xs,ys) 

推荐答案

你的功能几乎是正确的.let f = function 是 let f x = match x with 的简写，因此您不需要显式参数.此外，您的算法需要进行一些调整.

Your function is almost right. let f = function is shorthand for let f x = match x with so you don't need explicit args. Also, your algorithm needs some tweaking.

let rec interleave = function //same as: let rec interleave (xs, ys) = match xs, ys with
  |([], ys) -> ys
  |(xs, []) -> xs
  |(x::xs, y::ys) -> x :: y :: interleave (xs,ys)

interleave ([5;3;8],[2;9;4]) //output: [5; 2; 3; 9; 8; 4]

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