result_in_dart

Description:

result in dart

result_in_dart #
Dart implementation of Rust's [Result] type.
Result<T, E> is the type used for returning and propagating
errors. It is a class with the two variants, [Ok(T)] and [Err(E)].
where [T] is the type of a successful value and [E] is the type of an error.
Loosely based on https://doc.rust-lang.org/src/core/result.rs.html source code.
import 'package:result_in_dart/result_in_dart.dart';

enum Version {
version1,
version2;
}

Result<Version, String> parseVersion(int versionNum) {
if (versionNum == 1) {
return const Ok(Version.version1);
}

if (versionNum == 2) {
return const Ok(Version.version2);
}

return const Err('invalid version');
}

void main() {
final version = parseVersion(1);

// you can then unwrap...
if (version.isOk()) {
print('unwrap: working with version: ${version.unwrap()}');
} else {
print('unwrap: error parsing header: ${version.unwrapErr()}');
}

// or mapping...
parseVersion(1).mapOrElse(
(err) => print('mapOrElse: error parsing header: $err'),
(v) => print('mapOrElse: working with version: $v'),
);

// or using Dart 3.0 patterns...
if (version case Ok(value: Version v)) {
print('patterns: working with version: $v');
}

if (version case Err(value: String err)) {
print('patterns: error parsing header: $err');
}

// unwrapping using the ~ operator
final a = Ok(1);
final b = Ok(2);

print('~ operator: ${~a + ~b}');
}
copied to clipboard