Some / Maybe / Option / Result / Nullable
Can avoid semantic confusion caused by returning null when returning a value
like Haskel Maybe
Usage
Import
import 'package:some/index.dart'; // import all
Create
Maybe<int> some = Some(1);
Maybe<int> none = None();
Switch (dart > 3.0.0)
Maybe<int> some = Some(1);
var a = switch (some) {
Some(v: var v) => v,
null => 0
};
Check has value
some.isSome
none.isNone
some.has
Get value
if(some.has) {
some.val!
}
Monadic
some.map((v) => 'some');
some.then((v) => 'some');
some.flatMap((v) => Some('some'));
some.andThen((v) => Some('some'));
Logical
some.and(Some('some'));
some.andThen((v) => Some('some'));
some.or(Some('some'));
some.orElse(() => Some('some'));
some.xor(Some('some'));
Flatten
someSome.flatten();
Pattern matching
some.when(some: (v) => 'some', none: () => 'none');
some.some((v) => 'some');
none.none(() => 'none');
none.defaultVal('none');
none.defaultValFn(() => 'none');