dee_result 0.0.1

A default result for Dart and Flutter

dee_result

A library for handling results in Dart and Flutter in a safe and structured way.

📌 Overview

dee_result provides two main abstractions for handling asynchronous operations and their possible results:

• Either<L, R>: Represents a value that can be either Left (failure) or Right (success).
• Result<T>: Represents a result that can be Ok (success) or Error (failure).

📦 Installation

Add the dependency to your Flutter/Dart project:

dependencies:
  dee_result: ^0.0.1

Or install it directly via terminal:

dart pub add dee_result

🚀 How to Use

Either

Either<L, R> is useful for representing operations that may result in success (Right<R>) or failure (Left<L>).

import 'package:dee_result/dee_result.dart';

Either<String, int> divide(int a, int b) {
  if (b == 0) {
    return Left("Division by zero is not allowed");
  }
  return Right(a ~/ b);
}

void main() {
  final result = divide(10, 2);

  result.fold(
    (left) => print("Error: $left"),
    (right) => print("Result: $right"),
  );
}

Result

The Result<T> class encapsulates the result of an operation, indicating success (Ok<T>) or error (Error<T>).

import 'package:dee_result/dee_result.dart';

Result<int> safeDivide(int a, int b) {
  if (b == 0) {
    return Result.error(Exception("Division by zero"));
  }
  return Result.ok(a ~/ b);
}

void main() {
  final result = safeDivide(10, 0);

  switch (result) {
    case Ok(value):
      print("Success: $value");
    case Error(error):
      print("Error: ${error.error}");
  }
}

Safe Handling with runGuard

The runGuard function helps encapsulate asynchronous calls, automatically converting exceptions into an Either.

import 'package:dee_result/dee_result.dart';

Future<Either<Exception, String>> fetchData() async {
  return runGuard(() async {
    await Future.delayed(Duration(seconds: 1));
    return "Data loaded successfully";
  });
}

void main() async {
  final result = await fetchData();
  
  result.fold(
    (left) => print("Error: ${left.toString()}"),
    (right) => print("Success: $right"),
  );
}

Using Streams (runSGuard)

To capture errors in a Stream, use runSGuard:

import 'package:dee_result/dee_result.dart';

Stream<Either<Exception, int>> numberStream() async* {
  yield* runSGuard(() async* {
    for (int i = 1; i <= 5; i++) {
      if (i == 3) throw Exception("Stream error!");
      yield i;
    }
  });
}

void main() async {
  await for (final result in numberStream()) {
    result.fold(
      (left) => print("Error: ${left.toString()}"),
      (right) => print("Number: $right"),
    );
  }
}

📝 License

This project is licensed under the BSD license. See the LICENSE file for details.

📢 Contributions

Feel free to contribute! If you find any issues or have suggestions, open an issue or submit a pull request on GitHub.