optional 1.2.1+1

An implementation of the Optional type

Changelog

1.2.0

• Operators are now overloaded, so you can add, subtract, etc., Optionals. Any operation involving an empty Optional will return an empty Optional.
• Added examples.

1.1.0

• Optional.ofNullable() and Optional.empty() constructors are now const.
• Optional.of() constructor now throws ArgumentError when passed null, instead of NoValuePresentError.
• NoValuePresentError now extends StateError.

1.0.0

• Initial release