On Thu, Apr 26, 2012 at 5:05 PM, Joachim Breitner
Hi,
Am Mittwoch, den 25.04.2012, 18:36 +0300 schrieb Michael Snoyman:
I'm sure there are many better ways to approach the problem, and I can't speak to the complexity of implementation within GHC. I *can* say, however, that this would have saved me a lot of time in the example I gave above, and I'd bet many Haskellers have similar stories. This could be a huge debugging win across the board.
using TH (which I only reluctantly advocate for general usage) you can get good location information behaviour, see http://hackage.haskell.org/packages/archive/stm-stats/0.2.0.0/doc/html/Contr... (and its source) for one example. One would use this approach maybe with http://hackage.haskell.org/packages/archive/safe/0.3.3/doc/html/Safe.html#v:...
Greetings, Joachim
-- Joachim Breitner e-Mail: mail@joachim-breitner.de Homepage: http://www.joachim-breitner.de Jabber-ID: nomeata@joachim-breitner.de
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We actually use a similar technique in Yesod for logging[1]. But it requires actively using it in all libraries. In other words, unless the author of the library in question explicitly used $headLoc, this wouldn't help. [1] http://hackage.haskell.org/packages/archive/yesod-core/1.0.1.1/doc/html/Yeso...