NOption 0.2.0

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.

Option<Color> GetFavoriteColor(string username)
{
  if ("Emma".Equals(username))
  {
    return Color.Blue;
  }

  return Option.None;
}

Working with the result

To work with result, you can use Match (with named arguments to improve readability):

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

For convenience, it is also possible to directly unwrap the content. BUT it is not safe as it will throw and InvalidOperationException if none was returned.

var result = GetFavoriteColor("Edward");

try
{
  var favoriteColor = result.Unwrap();
}
catch (InvalidOperationException)
{
  // => Throws an InvalidOperationException!
}

Bonus

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

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