Use of runCatching and coroutines breaks structured concurrency about kotlin-result

[Munzey]

I also think a syntax like rethrow()<> for the specific result types where Err extends Exception reads better.

For cases where result Err is of some other type that does not extend exception, i think it would be difficult to make a more generic version of this function without throwing something, unless perhaps a third state was added to Result, something like Result.ExcludedErr where invoking things like onSuccess and onFailure on it do nothing.

[michaelbull]

@grodin separate PRs for each one would be best.

[grodin]

See this comment on the above linked issue for an example of what goes wrong.

[michaelbull]

The existing signature of runCatching is likely to stay true to whatever the stdlib does, I don't think its wise to deviate from that in terms of user expectations. I do however like the idea proposed here with the except function. Maybe we could make that work for more than just exceptions too. That also means that in future, the signature of runSuspendCatching would just be runCatching { it }.except<CancellationException>() or similar.

[grodin]

That's quite funny: I had exactly the same thought and that's exactly how I implemented runSuspendCatching in my own project!

I'd suggest a slightly better name for except(), like rethrow() or something to make it a bit clearer what it does.

I'm not quite sure what you mean by making that extra function rethrow or whatever work for things other than exceptions. If the error isn't an exception how do we throw it? Did you have something else in mind?

Do you want separate PRs, firstly for except/rethrow and then another for runSuspendCatching to keep the git history nice or just one PR with unsquashed commits?

[grodin]

I think you might have closed this prematurely. You've merged throwIf but that leaves runSuspendCatching still to implement. I've done that actually, and will send a PR as soon as I've rebased and written the kdoc but just in case, maybe this should be reopened.