Мир верх тормашками или код как данные

Pair.cs

using System;

namespace CodeAsData
{
    public class Pair
    {
        static void Main(string[] args)
        {
            var pair = create(1, 'a');
            Console.WriteLine(key(pair) + ":" + value(pair));
        }

        public static Func<Operation, object> create(object key, object value)
        {
            return delegate(Operation operation)
            {
                if (operation == Operation.Key)
                    return key;
                else if (operation == Operation.Value)
                    return value;
                else
                    throw new Exception("WTF?!");
            };
        }

        public static object key(Func<Operation, object> pair)
        {
            return pair(Operation.Key);
        }

        public static object value(Func<Operation, object> pair)
        {
            return pair(Operation.Value);
        }

        public enum Operation
        {
            Key, Value
        }
    }
}