Continuations

Ok, continuations is not the way we from the imperative world are use to think. Yet Another Language Geek defines it like this:

CPS (Continuation-Passing Style) turns a program inside-out. In the process, the programmer may feel that his brain has been turned inside-out as well.

He carries on defining some simple samples. Here's his factorial sample:

     static void fact(int n, Action<int> action)
    {
        if (n == 0)
        {
            action(1);
        }
        else
        {
            fact(n - 1, x => action(n * x));
        }
    }

    static void Main(string[] args)
    {
        fact(5, x => Console.WriteLine(x));
    }

Please follow the rest of the his post - it's loaded with samples usable on the real world.