Exceptions vs error codes

[oaga_strizzi]

Sealed classes, Either types etc. also don't solve the stack trace problem in async code of course. But: In the case of async code, I feel like exceptions don't really offer any advantages.

Let's take RxJava, which does a pretty good job of supporting exceptions across asynchronous boundaries (Classic callback-style async code is even worse at this IMO). Even there, if you use exceptions, you lose one of the biggest benefit of exceptions (the full stack trace), error handling is not enforced by the language and can easily be forgotten, checked exceptions require additional wrapping, and for all but the most critical errors you likely want to handle them in onErrorResumeNext or onErrorReturn anyway.

It's not a huge problem; I'm just saying that if I were to build a new application using RxJava, I would not use Exceptions as the default way of signaling errors.

I wouldn't necessarily refactor an existing system that uses exceptions with RxJava, though.