optional 3.0.0+1

An implementation of the Optional type

Changelog

3.0.0

• (Breaking change) Removed operator overloads. They were breaking strong-mode type checks.
• (Breaking change) Made equality checks more consistent with Dart standards. Now any two empty Optionals are equal, and two non-empty Optionals are equal if their values are equal, regardless of their types.
• Added a cast() method, similar to List.cast().

2.0.2

• Better use of generic methods (no more dynamic).

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