//Rextester.Program.Main is the entry point for your code. Don't change it.

//Compiler version 4.0.30319.17929 for Microsoft (R) .NET Framework 4.5

​

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text.RegularExpressions;

​

namespace Rextester

{

    public class Program

    {

        public interface Optional

        {

            bool IsNone {get;}

            bool IsSome {get;}

        }

        public interface None : Optional {}

        public interface Some<T>: Optional { T Value {get;  }}

        //public static class Option<T> : Optional

        //{

        //}

​

        public static class Option

        {              

             public static Optional None { get {return new Impl.None_();}}

             public static Optional Some<T>(T value) where T : class {

             if (value == null) return new Impl.None_(); else return new Impl.Some_<T>(value);}

             private static class Impl

              {

                 public struct None_ : None

                 {

                     public bool IsSome { get { return false;}}

                     public bool IsNone { get { return true; }}

                  }

                 public struct Some_<T> : Some<T>

                 {

                      private T value;

                      public bool IsSome { get { return true;}}

                      public bool IsNone { get { return false;}}

                      public T Value { get { return this.value;}}

                      internal Some_(T value){

                          this.value = value;}

                 }

             }

        }

​

        public static string PrintType(Optional obj)

        {

             if (obj is None) return "None";

             if (obj is Some<string>) return "Some: " + (obj as Some<string>).Value;

             return "Base";

        }

​

        public static void Main(string[] args)

        {

            var one = Option.None;

            var two = Option.Some("Hola");

            //Your code goes here

            Console.WriteLine(PrintType(one));

            Console.WriteLine(PrintType(two));

        }

    }

}