Alien Signals for Dart

The lightest signal library for Dart, ported from stackblitz/alien-signals.

Tip

Alien Signals is the fastest signal library currently, as shown by experimental results from 👉 dart-reactivity-benchmark.

Installation

To install Alien Signals, add the following to your pubspec.yaml:

dependencies:
  alien_signals: latest

Alternatively, you can run the following command:

dart pub add alien_signals

Basic Usage

import 'package:alien_signals/alien_signals.dart';

void main() {
  // Create a signal
  final count = signal(0);

  // Create a computed value
  final doubled = computed((_) => count.get() * 2);

  // Create an effect
  effect(() {
    print('Count: ${count.get()}, Doubled: ${doubled.get()}');
  });

  // Update the signal
  count.set(1); // Prints: Count: 1, Doubled: 2
}

Core Concepts

Signals

Signals are reactive values that notify subscribers when they change:

final name = signal('Alice');

print(name.get()); // Get value using `get` method.
name.set('Bob');   // Set value using `set` method.

Computed Values

Computed values automatically derive from other reactive values:

final firstName = signal('John');
final lastName = signal('Doe');
final fullName = computed((_) => '${firstName.get()} ${lastName.get()}');

effect(() => print(fullName.get())); // Prints: John Doe
lastName.set('Smith'); // Prints: John Smith

Effects

Effects run automatically when their dependencies change:

final user = signal('guest');
final e = effect(() {
  print('Current user: ${user.get()}');
});

// Cleanup when done
e.stop();

Effect Scopes

Group and manage related effects:

final scope = effectScope();
scope.run(() {
  // Effects created here are grouped
  effect(() => print('Effect 1'));
  effect(() => print('Effect 2'));
});

// Clean up all effects in scope
scope.stop();

API Reference

See the API documentation for detailed information about all available APIs.

License

This project is licensed under the MIT License - see the LICENSE file for details.

Credits

This is a Dart port of the excellent stackblitz/alien-signals library.