ILSpy/cecil/rocks/Mono.Cecil.Rocks/Functional.cs

//
// Functional.cs
//
// Author:
//   Jb Evain (jbevain@gmail.com)
//
// Copyright (c) 2008 - 2011 Jb Evain
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//

using System;
using System.Collections.Generic;

namespace Mono.Cecil.Rocks {

	static class Functional {

		public static System.Func<A, R> Y<A, R> (System.Func<System.Func<A, R>, System.Func<A, R>> f)
		{
			System.Func<A, R> g = null;
			g = f (a => g (a));
			return g;
		}

		public static IEnumerable<TSource> Prepend<TSource> (this IEnumerable<TSource> source, TSource element)
		{
			if (source == null)
				throw new ArgumentNullException ("source");

			return PrependIterator (source, element);
		}

		static IEnumerable<TSource> PrependIterator<TSource> (IEnumerable<TSource> source, TSource element)
		{
			yield return element;

			foreach (var item in source)
				yield return item;
		}
	}
}