Use Either<> from fpdart to enhance your Dart code

Use the power of functional programming to take your dart code to the next level

At a beginner level, let’s say you have a function with an API call for fetching the list of users inside a repository, something like this:

Future<List<User>> getUsers() async {
 var url = Uri.parse(‘https://jsonplaceholder.typicode.com/users');
 var response = await http.get(url);
 var list = jsonDecode(response.body) as List;
 return list.map((e) => UserJson.fromJson(e).toDomain()).toList();
}

For consuming this, your BLoC/Provider/Cubit or any other state management page-couple would probably look something like this:

Future<void> fetchUsers() async {
    emit(state.copyWith(isLoading: true));
    try {
      final users = await usersRepository.getUsers();
      emit(state.copyWith(users: users, isLoading: false));
    } catch (ex) {
      // print or log your error
      emit(
        state.copyWith(
          error: MyErrorClass(errorString: ex.toString()),
          isLoading: false,
        ),
      );
    }
  }

And given your app’s pages, features, API calls, it’s going to get blotchy when you have a lot of BLoC/Cubit/Provider files with lots of API calls. Furthermore, this BLoC/Cubit/Provider should not worry about…