https://github.com/ookami-kb/dfunc

Functional batteries for Dart programming language.
https://github.com/ookami-kb/dfunc

dart dart-library dart-package dart2 dartlang functional-batteries

Last synced: 13 days ago
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Functional batteries for Dart programming language.

• Host: GitHub
• URL: https://github.com/ookami-kb/dfunc
• Owner: ookami-kb
• License: bsd-2-clause
• Created: 2019-09-07T17:52:07.000Z (about 5 years ago)
• Default Branch: master
• Last Pushed: 2024-06-03T16:29:10.000Z (5 months ago)
• Last Synced: 2024-10-12T18:06:42.993Z (27 days ago)
• Topics: dart, dart-library, dart-package, dart2, dartlang, functional-batteries
• Language: Dart
• Homepage: https://pub.dev/packages/dfunc
• Size: 166 KB
• Stars: 20
• Watchers: 4
• Forks: 3
• Open Issues: 1
• Metadata Files:
  • Readme: README.md
  • Changelog: CHANGELOG.md
  • License: LICENSE

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README

        
![](https://github.com/ookami-kb/dfunc/workflows/Dart%20CI/badge.svg)

[![Pub Version](https://img.shields.io/pub/v/dfunc)](https://pub.dev/packages/dfunc)

[![codecov](https://codecov.io/gh/ookami-kb/dfunc/branch/master/graph/badge.svg?token=K70NTIMBR5)](https://codecov.io/gh/ookami-kb/dfunc)

Lightweight and practical functional library for Dart programming language.

The goal of this library is not having deep and hardcore FP features. If you need them, take a look

at [dartz](https://pub.dev/packages/dartz) package.

`dfunc` instead, provides some practical features based on FP principles, that we use extensively in our production

codebase. We try to keep the library aligned with "Dart way" of doing things, instead of turning it into Haskell or

Scala :)

## Optional

There's no `Optional` type. Since nullsafety is introduced, nullable types cover the majority of use-cases for them.

Instead, `dfunc` provides you some extensions for nullable types.

### maybeMap and maybeFlatMap

```dart

void main() {

  String? x = null;

  x.maybeMap((x) => x.toUpperCase()); // null

  x = 'test';

  x.maybeMap((x) => x.toUpperCase()); // 'TEST'

  x.maybeFlatMap((x) => x == 'test' ? 'OK' : null); // 'OK'

}

```

Both `maybeMap` and `maybeFlatMap` can be replaced with `let` if you prefer Kotlin-style:

```dart

void main() {

  String? x = null;

  x?.let((x) => x.toUpperCase()); // null

  x = 'test';

  x?.let((x) => x.toUpperCase()); // 'TEST'

  x?.let((x) => x == 'test' ? 'OK' : null); // 'OK'

}

```

The differences are:

- you don't need `?.` with `maybe*` functions, they unwrap the value automatically;

- you can enforce the function in `maybeMap` to return non-nullable result.

### maybeWhere

Same as you can filter the list with `where` method to remove undesired values (and probably get an empty list), you can

use `maybeWhere` to "filter" optional value. As a result you will get either the value itself, or null if the condition

is not satisfied:

```dart

void main() {

  final List a = [1];

  a.where((e) => e == 1); // [1]

  a.where((e) => e == 2); // []

  final int b = 1;

  b.maybeWhere((e) => e == 1); // 1

  b.maybeWhere((e) => e == 2); // null

}

```

## Either

`TBD`

## Utilities

`TBD`

## Features and bugs

Please file feature requests and bugs at the [issue tracker](https://github.com/ookami-kb/dfunc/issues).