lamada形式處理遞歸的通用方法

從老趙那學一招，不動點理論：
http://blogs.msdn.com/madst/archive/2007/05/11/recursive-lambda-expressions.aspx

 

using System; class Program { //Fix不動子函數,記住就行了. static Func<T, TResult> Fix<T, TResult>(Func<Func<T, TResult>, Func<T, TResult>> f) {return x => f(Fix(f))(x);} static void Main() { //遞歸函數的定義，階乘：f(x)=x*f(x-1) var fac = Fix<int, int>(f => x => x <= 1 ? 1 : x * f(x - 1)); //方法執行 Console.WriteLine(fac(5)); Console.ReadKey(); } }