ben, could you please email the libraries list with this too? This seems like a core libraries / base change rather than a ghc-the-compiler change
On Thu, May 7, 2020 at 6:57 PM Michael Sloan <mgsl...@gmail.com> wrote: > Thanks so much for making a proposal for this, Ben!! It's great to see > progress here. > > I'm also glad that there is now a proposal process. I made a fairly > similar proposal almost exactly 5 years ago to the libraries list - > https://mail.haskell.org/pipermail/libraries/2015-April/025471.html - but > without the subtlety of particular backtrace representations. Skimming the > ensuing thread may still be informative. > > In particular, there is one thing I would like to highlight from that old > proposal. I think it'd be good to have a standard way to represent a chain > of exceptions, and build this into `catch` and `finally`. Python and Java > both have a mechanism for this, and both refer to it as a "cause" > exception. When an exception is thrown during exception handling, the > exception being handled is preserved as its "cause". I find this mechanism > to be incredibly useful in Java, it has made the underlying issue much > clearer in many cases, and in other cases at least provides helpful > context. I have no doubt such a mechanism would have saved me many hours > of debugging exceptions in Haskell systems I've worked on in the past. > > I considered commenting about that directly on the proposal, but I figure > this is a better place to suggest expanding the scope of the change :) . > Totally understandable if you want to keep this proposal focused on > stacktraces, but I think it'd be good to consider this as a potential > future improvement. > > -Michael > > On Thu, May 7, 2020 at 3:55 PM Ben Gamari <b...@well-typed.com> wrote: > >> >> Hi everyone, >> >> After a nice discussion on IRC about the unfortunate state of error >> reporting in Haskell, I felt compelled to write down some long-lingering >> thoughts regarding backtraces on exceptions. The result is GHC proposal >> #330 [1]. I think the approach is viable and perhaps even >> straightforward. I have the sketch of an implementation here [2]. >> >> Please have a look at the proposal and leave your comments. If there is >> consensus it is possible that we could have this done for 8.12. >> >> Cheers, >> >> - Ben >> >> >> [1] https://github.com/ghc-proposals/ghc-proposals/pull/330 >> [2] https://gitlab.haskell.org/ghc/ghc/-/merge_requests/3236 >> _______________________________________________ >> ghc-devs mailing list >> ghc-d...@haskell.org >> http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs >> > _______________________________________________ > ghc-devs mailing list > ghc-d...@haskell.org > http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs >
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