some 1.2.3

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

Some / Maybe / Option / Result / Nullable

Can avoid semantic confusion caused by returning null when returning a value

like Haskel Maybe

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Usage

Import

import 'package:some/index.dart'; // import all

import 'package:some/maybe.dart'; // only class Maybe
import 'package:some/some.dart'; // only class Some
import 'package:some/none.dart'; // only class None

import 'package:some/null.dart'; // only no null function

Create

Maybe<int> some = Some(1);

Maybe<int> none = None();

Maybe<int> some = Maybe(1);

Maybe<int> some = Maybe.Some(1);

Maybe<int> none = Maybe.None();

GetValue

if(some.has) {
    some.val
}

Pattern matching

if(some is Some) {}

if(some is Some<int>) {}

if(some is None) {}

some.when(some: (v) => 'some', none: () => 'none');

some.some((v) => 'some');

none.none(() => 'none');

none.defaultVal('none');

none.defaultValFn(() => 'none');

Note

Compare the actual wrapped value when comparing
This is useful in some cases, but you need to be careful when mixing the use of normal values and Maybe values, you need check it is Some

Some(1) == 1
// true

None() == None()
// true