using System;

public class Program

{

    public static void Main()

    {

        Either<X, Y> dontKnowWhich = GetXOrY();

        PrintEither(dontKnowWhich);

    }

    public static Either<X, Y> GetXOrY()

    {

        var rand = new Random();

        if(rand.Next(1,3) == 1) return new X();

        else return new Y();

    }

    public static void PrintEither(Either<X, Y> either)

    {

        var result = either.Match((x) => x.Value, (y) => y.Value); 

        Console.WriteLine(result);

    }

}

​

public class X {

    public string Value => "X";

}

​

public class Y {

    public string Value => "Y";

}

​

public class Either<T1, T2>

{

    int index { get; set; }

    object _value { get;set; }

    public Either(T1 t1) { 

        index = 0;

        _value = t1;

    }

    public Either(T2 t2) { 

        index = 1;

        _value = t2;

    }

    public TResult Match<TResult>(Func<T1, TResult> f1, Func<T2, TResult> f2)

    {

        if(index == 0) return f1((T1)_value);

        if(index == 1) return f2((T2)_value);

        throw new Exception();

    }

    public static implicit operator Either<T1, T2>(T1 t1) => new Either<T1, T2>(t1);

    public static implicit operator Either<T1, T2>(T2 t2) => new Either<T1, T2>(t2);

}