using System;
using System.Collections.Generic;

public static class ListApplyAndFunction
{
	public static List<TResult> Apply<TResult, TInput>(this IEnumerable<TInput> input, ListApplyAndFunction.Function<TResult, TInput> function, bool discardNulls = false)
	{
		List<TResult> list = new List<TResult>();
		foreach (TInput arg in input)
		{
			TResult tresult = function(arg);
			if (!discardNulls || tresult != null)
			{
				list.Add(tresult);
			}
		}
		return list;
	}

	public delegate TResult Function<out TResult, TArg1>(TArg1 arg1);

	public delegate TResult Function<out TResult, TArg1, TArg2>(TArg1 arg1, TArg2 arg2);

	public delegate TResult Function<out TResult, TArg1, TArg2, TArg3>(TArg1 arg1, TArg2 arg2, TArg3 arg3);
}