List Monad implemented in C#

Program.cs

using System;
using System.Collections.Generic;
using System.Linq;

namespace Monad
{
	class Program
	{
		static void Main(string[] args)
		{	
			// Equivalent to: fmap show [1..3]
			var result1 = FMap(Enumerable.Range(1,3), x => x.ToString());

			// Equivalent to: (+) <$> [1,2,3] <*> [1,2,3]
			var result2 = 
				Apply(Enumerable.Range(1, 3),
				FMap<int, Func<int,int>>(Enumerable.Range(1, 3), x => (y => x + y)));

			// Equivalent to:  [1..3] >>= (\x -> [1..3] >>= (\y -> return (x,y)))
			//            or:  do; x <- [1..3]; y <- [1..3]; return (x,y)
			//            or:  [(x,y) | x <- [1..3], y <- [1..3]]
			var result3 = 
				Bind(Enumerable.Range(1,3), x =>
				Bind(Enumerable.Range(1,3), y =>
 					Pure(Tuple.Create(x,y))));
		}

		static IEnumerable<T> Pure<T>(T val)
		{
			yield return val;
		}

		static IEnumerable<U> Bind<T,U>(IEnumerable<T> mt, Func<T, IEnumerable<U>> f_t_mu)
		{
			return mt.SelectMany(f_t_mu);
		}

		static IEnumerable<U> Apply<T,U>(IEnumerable<T> mt, IEnumerable<Func<T,U>> m_f_t_u)
		{
			return Bind(mt, t => Bind(m_f_t_u, f => Pure(f(t))));
		}

		static IEnumerable<U> FMap<T, U>(IEnumerable<T> mt, Func<T,U> f_t_u)
		{
			return Apply(mt, Pure(f_t_u));
		}
	}

}

List Monad implemented in C# (pure, bind).
Apply and FMap derived in 'generic' way using only pure/bind and without directly using the IEnumerable interface.

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