NOption

NOption is a concise and fluent implementation of the Option pattern for the .NET platform.

Usage

Add the library namespace

Simply import the NOption namespace:

import NOption;

Use Option<> as the return type

To start using NOption:

• Change your function return type to Option<>;
• The return value will implicitely be wrapped in an Option<>;
• To specify that there is no return value, use Option.None.

static Option<Color> GetFavoriteColor(string username)
{
	if ("Emma".Equals(username))
	{
		return Option.Some(Color.Blue);
	}
	return Option.None<Color>();
}

Working with the result

To work with result, you can use Match:

var result = GetFavoriteColor("Emma");
result.Match(
	Some: (favoriteColor) => Console.WriteLine($"Emma likes the color {favoriteColor}."),
	None: () => Console.WriteLine("Emma does not have a favorite color.")
);
// Print "Emma likes the color Blue"

You can also unwrap the content with a default value:

var result = GetFavoriteColor("Mark");
var favoriteColor = result.UnwrapOr(Color.Purple); // Returns Color.Purple

Or you can extract the value:

var result = GetFavoriteColor("Emma");
if (result.HasSome(out var favoriteColor))
{
	Console.WriteLine($"Emma likes the color {favoriteColor}.");
}

Bonus

To rewrite GetFavoriteColor as a one line function, we could have use:

static Option<Color> GetFavoriteColor(string username)
{
  return Option.Some(Color.Blue, when: "Emma".Equals(username));
}