optional 2.0.1+2

An implementation of the Optional type

Changelog

2.0.0

• Compatibility with Dart 2

1.2.3

• Add an optional orElse parameter to ifPresent.

1.2.2

• Optional.empty() constructor is now const.

1.2.1

• Absent and Present are now subclasses of Optional. You should continue to use constructors in Optional, and not the Absent or Present ones.
• EMPTY is now a top-level constant.

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