Exception handling in streams

[jroper]

All of the streams callbacks are using java.util.function.*, which don't allow throwing checked exceptions. Should we allow streams to be completed with checked exceptions, by providing a wrapper unchecked exception that gets unwrapped when caught? java.util.concurrent.CompletionException could be a candidate to use.

One argument for not doing this is that CompletionStage doesn't do it, so it may worth being consistent in behavior with CompletionStage. On the other hand, it's much nicer for users to not have to unwrap exceptions.

[Emily-Jiang]

I don't quite understand your use case here. Please elaborate more. Introducing something inconsistence to the CompletionStage will confuse users.

[cescoffier]

On this topic I recent found https://github.com/pivovarit/throwing-function.

We may want to come up with our own Exception as it would be part of the contract and not a bad/odd usage of CompletionException.

[Emily-Jiang]

How about defining our own exception ReactiveStreamsCompletionException?

[Emily-Jiang]

Based on @cescoffier , he implemented on mutiny but it is not useful.