Likewise: very supportive, a few holes that I'd like to address before fully committing. Contrary to Simon M, though, I think I prefer the implicit parameter design to the pattern-synonym design. On Thu, 9 Mar 2023 at 11:23, Simon Marlow wrote:

High-level we definitely want this, I added a couple of comments to the GitHub thread to discuss details.

One slightly suboptimal aspect of the proposal is the use of implicit parameters. The design in Section 8.2 https://github.com/bgamari/ghc-proposals/blob/stacktraces/proposals/0000-exc... seems much nicer and is only prevented by issues with pattern synonyms. Couldn't we fix pattern synonyms so this would work?

Cheers Simon

On Mon, 6 Mar 2023 at 13:44, Vladislav Zavialov wrote:

...

Dear Committee,

Ben Gamari has proposed #330 "Decorate exceptions with backtrace information". Read it here:

https://github.com/bgamari/ghc-proposals/blob/stacktraces/proposals/0000-exc...

The proposal attaches contextual information to thrown exceptions. This information includes (but is not limited to) backtraces, making it possible to debug uncaught exceptions more effectively.

This is a very nuanced change, since it modifies SomeException, throw, catch, and other exception-related definitions whose use is extremely widespread. We might end up affecting our users in unexpected ways. Because of that, I ask the committee to review the proposal with the appropriate amount of care.

I am recommending acceptance because adding observability to our programs is an important part of developer ergonomics. From the proposal discussion, I have got the impression that there are numerous commercial users who would benefit from this.

Please take a look at the proposal text and share your thoughts either here or directly on GitHub.

- Vlad _______________________________________________ ghc-steering-committee mailing list ghc-steering-committee@haskell.org https://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-steering-committee

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On Thu, 9 Mar 2023 at 12:52, Simon Marlow wrote:

Out of interest, why?

I'm not sure that I can quite say. The idea of annotations being somewhat implicitly passed, the symmetry with `HasCallStack`: it appeals to me. I guess it's not a very strong preference.

Dear Committee, Back in March I recommended to accept GHC Proposal #330 "Decorate exceptions with backtrace information". It appears to me that we all agree that the proposed change is a good idea. There were a couple of technical suggestions that the author readily incorporated into the proposal text (the most important addition: nested `WhileHandling` annotations). I've skimmed the proposal one more time before writing this message and I find that it is in a very good state now. I'm about to declare it accepted, any last moment objections? Vlad On Fri, Mar 10, 2023 at 8:47 AM Arnaud Spiwack wrote:

My questions have been addressed, I'm now content with the proposal.

On Thu, 9 Mar 2023 at 18:03, Arnaud Spiwack wrote:

...

On Thu, 9 Mar 2023 at 12:52, Simon Marlow wrote:

...

Out of interest, why?

I'm not sure that I can quite say. The idea of annotations being somewhat implicitly passed, the symmetry with `HasCallStack`: it appeals to me. I guess it's not a very strong preference.