Tristan Allwood got quite a long way with this a couple of years ago. http://research.microsoft.com/en-us/um/people/simonpj/papers/stack-trace/Deb... But not enough to finish it off! The paper describes the tricky points... Simon M is more of an expert than I. Moreover the work Simon has done on improving profiling is relevant too. Simon | -----Original Message----- | From: haskell-cafe-bounces@haskell.org [mailto:haskell-cafe- | bounces@haskell.org] On Behalf Of Evan Laforge | Sent: 25 April 2012 17:08 | To: Michael Snoyman | Cc: Haskell Cafe | Subject: Re: [Haskell-cafe] Printing call site for partial functions | | > And then have the compiler automatically include (optional) package | > name, module name, and line number where `headContext` was called. How | > about we borrow a bit from rewrite rules, and have a pragma such as: | > | > {-# WITH_CONTEXT head headContext #-} | | This seems similar to the SRCLOC_ANNOTATE pragma supported by jhc. | | I'd love to have this feature. I'd just like to point out it's not just | useful for partial functions like 'head', but also for logging and "expected" | exceptions like Left. It's also extremely useful for tests, when I get | "check failed: 3 /= 4" it's really important to see filename and line number. | | There are various hacks out there to get this, but they all involve | annotating the call sites with some magic, either an 'assert' (and then | runtime overhead on every function that uses it) or a TH splice (and then you | have to turn TH on in every module). I have literally thousands of lines of | tests that would all need an extra boilerplate argument. | | I implemented a preprocessor that is effectively like SRCLOC_ANNOTATE and it | works ok for me, but it's not a good general solution because it's hardcoded | to certain symbols and slows down compilation too much. | And being specific to my app of course it wouldn't help in your case | :) | | But it won't happen unless one of us few people who care about it just goes | and implements it. I don't think it's much of a priority with others. | | _______________________________________________ | Haskell-Cafe mailing list | Haskell-Cafe@haskell.org | http://www.haskell.org/mailman/listinfo/haskell-cafe