c# - C# 是否支持函数组合？

Question

在最新版本的C#中，我可以做类似Haskell的函数组合吗？ more... ？

Function composition is the act of pipelining the result of one function, to the input of another, creating an entirely new function.

我觉得 linq 是最接近的，但那是链接，而不是函数组合，对吧？

Answer 1

public static class Extensions
{
    public static Func<T, TReturn2> Compose<T, TReturn1, TReturn2>(this Func<TReturn1, TReturn2> func1, Func<T, TReturn1> func2)
    {
        return x => func1(func2(x));
    }
}

用法:

Func<int, int> makeDouble = x => x * 2;
Func<int, int> makeTriple = x => x * 3;
Func<int, string> toString = x => x.ToString();
Func<int, string> makeTimesSixString = toString.Compose(makeDouble).Compose(makeTriple);

//Prints "true"
Console.WriteLine(makeTimesSixString (3) == toString(makeDouble(makeTriple(3))));