flutter_resultable

A lightweight, expressive Result type for Flutter and Dart to model success and failure outcomes without using exceptions, inspired by functional programming patterns like Either.

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✨ Features

  • ✅ Result.success(S) and Result.failure(F) to represent outcomes cleanly.
  • 🔁 Pattern matching via when, map, and maybeWhen (thanks to freezed).
  • ⚡ Strongly typed failure and success handling.
  • 🧠 Utility extensions:
    • isSuccess, isFailure
    • successOrNull, failureOrNull
    • getOrElse(fallback)
    • fold(onFailure, onSuccess)
  • 💡 Easily testable and composable.
  • 🪶 Minimal, clean API.

📦 Installation

Add this to your pubspec.yaml:

dependencies:
  flutter_resultable: ^0.0.3

Then run:

flutter pub get

🔧 Usage

Define a result-returning function

import 'package:flutter_resultable/flutter_resultable.dart';

Result<String, int> divide(int a, int b) {
  if (b == 0) return Result.failure("Division by zero");
  return Result.success(a ~/ b);
}

Handle with pattern matching

final result = divide(10, 2);

result.when(
  failure: (error) => print("Error: $error"),
  success: (value) => print("Result: $value"),
);

Use maybeWhen for optional handling

result.maybeWhen(
  success: (value) => print("Success with $value"),
  orElse: () => print("Something went wrong"),
);

Use fold for cleaner branching

result.fold(
  (error) => print("Error: $error"),
  (value) => print("Value: $value"),
);

Use getOrElse to provide a fallback value

final value = result.getOrElse((error) => -1); // returns 5 or -1

Check result state or access nullable values

if (result.isSuccess) {
  print(result.successOrNull);
} else {
  print(result.failureOrNull);
}

📘 API

sealed class Result<F, S> {
  const factory Result.failure(F failure) = Failure<F, S>;
  const factory Result.success(S success) = Success<F, S>;
}

Utility Extensions

Extension Description
isSuccess Returns true if the result is success
isFailure Returns true if the result is failure
successOrNull Returns success value or null
failureOrNull Returns failure value or null
getOrElse Fallback mechanism based on failure value
fold Branching on both success and failure cases

💰 Support

If you find this project helpful, consider sponsoring me on GitHub 💖

🙌 Contributing

Contributions, ideas, and pull requests are welcome. Let’s make flutter_resultable better together!

🙏 Thanks

This package is powered by the amazing freezed package. Special thanks to Remi Rousselet and contributors for their work.

Without freezed, clean and expressive sealed classes like Result wouldn't be this simple ✨

📄 License

MIT License

🔗 Useful Links

Libraries

flutter_resultable