Jose's failure to understand Maybe :)

Maybe.cs

using System;
using System.Collections.Generic;
using System.Linq;

namespace Playground.Utils
{
    public struct Maybe<T>
    {
        readonly IEnumerable<T> _values;

        public static Maybe<T> Some(T value)
        {
            if (value == null)
            {
                throw new InvalidOperationException();
            }

            return new Maybe<T>(new[] { value });
        }

        public static Maybe<T> None => new Maybe<T>(new T[0]);

        private Maybe(IEnumerable<T> values)
        {
            this._values = values;
        }

        public bool HasValue => _values != null && _values.Any();

        public T Value
        {
            get
            {
                if (!HasValue)
                {
                    throw new InvalidOperationException("Maybe does not have a value");
                }

                return _values.Single();
            }
        }

        public U Case<T, U>(Func<T, U> some, Func<U> none)
        {
            return this.HasValue
                       ? some(Value)
                       : none();
        }
    }
}

Case should be

public U Case<U>(Func<T, U> some, Func<U> none)
{
    return this.HasValue 
        ? some(Value)
        : none();
}