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-exception-backtraces.rst

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.

- VladÂ