Useful extensions on Result class of async package.

Features

• FutureResult<T> alias for Future<Result<T>>
• Result<U> map<U>(U Function(T) f);
• Result<T> mapError<E extends Object>(E Function(Object error, StackTrace? stackTrace) f);
• Result<U> flatMap<U>(Result<U> Function(T) f);
• U fold<U>(U Function(T value) onSuccess, U Function(Object error, StackTrace? stackTrace) onError);
• T getOrElse(T Function() orElse);
• T getOrThrow();
• void match({ void Function(T value)? onSuccess, void Function(Object error, StackTrace? stackTrace)? onError });
• void forEach(void Function(T) f)

Usage

final username = await fetchResult(withError: false).fold(
  (user) => user.username,
  (error, _) => 'Cannot fetch user: $error',
);
print(username); // john

final usernameNotOk = await fetchResult(withError: true).fold(
  (user) => user.username,
  (error, _) => 'Cannot fetch user: $error',
);
print(usernameNotOk); // Cannot fetch user: Some Failure happened

final helloUser =
    await fetchResult(withError: false).map((r) => 'hello ${r.username}');
print(helloUser.getOrElse(() => 'Hello, anonymous')); // hello john