option_result 3.2.0
option_result: ^3.2.0 copied to clipboard
A lightweight Dart library for Rust-like Option/Result types. Supports exhaustive pattern matching and provides helpers for None()/Err() propagation
example/option_result_example.dart
import 'dart:math';
import 'package:option_result/option_result.dart';
Random random = Random();
void main() async {
// Get a user object from the database
Result<User, String> user = await getUser(id: 12345);
// If it's an Err type value, display the unwrapped error value and return
if (user case Err(value: String error)) {
print('Error retrieving user: $error');
return;
}
// Try getting the user's email address
Option<String> email = user.unwrap().email;
// If the user has an email address, print it
if (email case Some(value: String address)) {
print('User email: $address');
} else {
print('User has no email set');
}
// Alternative to the above using a switch expression for pattern matching
String message = switch (email) {
Some(value: String address) => 'User email: $address',
None() => 'User has no email set'
};
print(message);
}
/// Represents a user in a database
class User {
int id;
Option<String> email;
User(this.id, this.email);
}
/// Simulate pulling a user from a database
Future<Result<User, String>> getUser({required int id}) async {
await Future.delayed(Duration(milliseconds: 100));
int randInt = random.nextInt(3);
return switch (randInt) {
0 => Ok(User(id, Some('foo$id@bar.com'))),
1 => Ok(User(id, None())),
2 => Err('User $id not found'),
_ => Err('Something went wrong')
};
}