avoidNull.csx

public struct Option<T>
{
    private readonly T _value;

    public T Value
    {
        get
        {
            if (!HasValue)
                throw new InvalidOperationException();

            return _value;
        }
    }

    public bool HasValue
    {
        get { return _value != null; }
    }

    public Option(T value)
    {
        _value = value;
    }

    public static implicit operator Option<T>(T value)
    {
        return new Option<T>(value);
    }
}

public class User
{
    public int Id;
    public string Name;
}

public Option<User> GetUser(int id)
{
    var users = new List<User>
    {
        new User { Id = 1, Name = "Joe Bloggs" },
        new User { Id = 2, Name = "John Smith" }
    };

    var u = users.FirstOrDefault(user => user.Id == id);

    return u != null ? new Option<User>(u) : new Option<User>();
}

var maybeUser = GetUser(2);
var username = maybeUser.HasValue ? maybeUser.Value.Name : string.Empty;
System.Console.WriteLine("username: " + username);