That looks like exactly what I want. Thanks. There remain two mysteries: - I thought that CallStacks were a new feature that would come with GHC 8.0. Yet it seems the datatype is present in base-4.8.x. Even though the docs even say (wrongly, evidently) that it's in base since 4.9.
- That function seems missing in HEAD. Or maybe it moved. A little searching says it *did* move, to GHC.Exception. Well, my problem is solved. But I think the documentation needs a pass here. And is there a reason not to have a Show instance? Thanks! Richard On Dec 6, 2015, at 11:48 PM, Levent Erkok <erk...@gmail.com> wrote: > There's a function for that: > https://hackage.haskell.org/package/base-4.8.1.0/docs/GHC-Stack.html#v:showCallStack > > > > On Sun, Dec 6, 2015 at 8:43 PM, Richard Eisenberg <e...@cis.upenn.edu> wrote: > Hi devs, > > I wish to use the new CallStack feature to track call sites of a function. I > want my function to print out where it was called from. I do not want to call > `error`. How do I do this? > > I looked in the release notes. They describe the CallStack feature at an > overview, and the docs suggest that it has a Show instance. But the notes > don't say where to import CallStack from. I found it in GHC.Stack, but I'm > unsure this is the right place to take it from. The GHC release notes also > refer me to the ghc-prim release notes. These (which I assume are > ghc-prim/changelog.md) don't discuss CallStack. In any case, when I try to > `show ?callstack`, I learn that CallStack is not an instance of Show, or I > somehow haven't imported the instance. > > Help? > > Thanks! > Richard > _______________________________________________ > ghc-devs mailing list > ghc-devs@haskell.org > http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs >
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