How to use chainEither on taskEither about fpdart

[radikz]

Ah right. thanks for the kind response.
Closed for now. ^^

[radikz]

I already solved it with

TaskEither<AppError, Response> _request(String url) => TaskEither<AppError, Response>.tryCatch(
        () async => await dio.get(url),
        (error, stackTrace) => AppError.from(error as Exception),
      ).chainEither(
        (response) => Either.tryCatch(
          () {
            if (response.statusCode != 200){
              Either.left(AppError.fromResponse(response));
            }
            return response;
          },
          (_, __) => AppError.fromResponse(response),
    ),
  );

I changed it from Either.fromPredicate to Either.tryCatch
I am not sure if this is best practice of fp.

[SandroMaglione]

Hi @radikz

In your first example the issue is that _validResponseBody returns Either<E, String>, while the type on your TaskEither is TaskEither<AppError, Response> (so Response instead of String). That's because you are mapping (map) the Response to String using .map((r) => r.data);.

Your second example works because in your tryCatch you just return Response (return response;) instead of response.data.

Does this make it more clear?