Code listing for http://blog.robustsoftware.co.uk/2010/04/currying-with-c.html

Fn.cs

using System;

namespace Currying
{
    public static class Fn
    {
        public static Func<Func<int>, Func<int>> Curry(Func<Func<int>, Func<int>> x, Func<Func<int>, Func<int>> y)
        {
            return a => y(x(a));
        }

        public static Func<int> Sum(Func<int> x, Func<int> y)
        {
            return Literal(x() + y());
        }

        public static Func<Func<int>, Func<int>> Sum(Func<int> x)
        {
            return y => Sum(x, y);
        }

        public static Func<int> Multiply(Func<int> x, Func<int> y)
        {
            return Literal(x() * y());
        }

        public static Func<Func<int>, Func<int>> Multiply(Func<int> x)
        {
            return y => Multiply(x, y);
        }

        public static Func<int> Literal(int x)
        {
            return () => x;
        }
    }
}

Program.cs

using System;

namespace Currying
{
    class Program
    {
        static void Main()
        {
            Func<Func<int>, Func<int>> addTwo = Fn.Sum(Fn.Literal(2));
            Func<int> three = addTwo(Fn.Literal(1));

            Func<Func<int>, Func<int>> timesThree = Fn.Multiply(Fn.Literal(3));
            Func<Func<int>, Func<int>> addTwoTimesThree = Fn.Curry(addTwo, timesThree);

            Func<int> twentyOne = addTwoTimesThree(Fn.Literal(5));
        }
    }
}