some 1.2.1

Some / Maybe / Option / Result / Nullable, like Haskel Maybe, Can avoid semantic confusion caused by returning null when returning a value

1.2.1

Fix bug(null.dart): defaultVal and defaultValFn when Some while return None

1.2.0

Fix bug: defaultVal and defaultValFn when Some while return None

1.1.1

const None

1.1.0

Add const constructor

1.0.1

Add example

1.0.0

Create this