Continuation monad in C#

Program.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication1
{
    public static class Program
    {
        delegate Answer K<T, Answer>(Func<T, Answer> k);

        static K<T, Answer> ToContinuation<T, Answer>(this T value)
        {
            return (Func<T, Answer> c) => c(value);
        }

        static K<V, Answer> SelectMany<T, U, V, Answer>(this K<T, Answer> m, Func<T, K<U, Answer>> k, Func<T, U, V> s)
        {
            return (Func<V, Answer> c) => m((T x) => k(x)(y => c(s(x, y))));
        }

        static void Main(string[] args)
        {
            var r = from x in 7.ToContinuation<int, string>()
                    from y in 6.ToContinuation<int, string>()
                    select x + y;

            var s = 7.ToContinuation<int, string>().SelectMany(x => 6.ToContinuation<int, string>(), (x, y) => x + y);

            Console.WriteLine(r(z => z.ToString().Replace('1', 'a'))); // displays a3
            Console.WriteLine(s(z => z.ToString().Replace('1', 'a'))); // displays a3

            Console.ReadLine();
        }
    }
}