Use LINQ query expressions without requiring IEnumerables, to compose functions.

gistfile1.cs

// Full credit goes to Wes Dyer http://blogs.msdn.com/b/wesdyer/archive/2008/01/11/the-marvels-of-monads.aspx
// Explanation of how query expressions are translated in to extension method syntax.

public class Identity<T>
{
    public T Value { get; private set; }
    public Identity(T value) { this.Value = value; }
	
	public static implicit operator Identity<T>(T value) {
	    return new Identity<T>(value);
	}
}

static class MonadicExtensions
{	
    // "Hijack" LINQ query expressions so that IEnumerable<T> isn't a requirement.
	public static Identity<Z> SelectMany<T,R,Z>(
		this Identity<T> source,
		Func<T, Identity<R>> function,
		Func<T,R,Z> s) {
	
		T unwrapped = source.Value;
		
		Identity<R> result = function(unwrapped);
		
		return s(unwrapped, result.Value);
	}
	
	public static Identity<T> ToIdentity<T>(this T value) {
		return value;
	}
}
 
void Main()
{
    // Returns Identity<int>, not IEnumerable or IQueryable.
	var results = 
		from x in 5.ToIdentity()
		from y in 10.ToIdentity()
		select x + y;
	
	Console.WriteLine (results);
}