Can you give the actual source code for the offending program, please? Simon | -----Original Message----- | From: Derek Elkins [mailto:ddarius86@hotmail.com] | Sent: 13 February 2003 20:29 | To: template-haskell@haskell.org | Subject: [Template-haskell] Instance declarations | | My first email seems to have gotten lost, if it meanders it's way here, then | sorry for the repeat. | | Anyways, generating a set of pattern matching functions in an instance | declaration (maybe in general, though I haven't tested it) causes a | "conflicting definitions error". Rewriting as a case expression is one | work-around. | | E.g. | | instance (NFData a) => NFData (Tree a) where | rnf (Leaf a) = rnf a | rnf (Branch a b) = rnf a `seq` rnf b | | doesn't work, but rewriting as | | instance (NFData a) => NFData (Tree a) where | rnf x = case x of | (Leaf a) -> rnf a | (Branch a b) -> rnf a `seq` rnf b | | does. | | I suspect that it may have to do with the generated code being considered at | a lower level (i.e. the transformation of the above into the below is | already considered done). It may just be I'm creating the functions | incorrectly, so if you can't get the error to happen I can provide the code | I'm using. | | Separately: I've written a variety of fold algebras over data declarations. | I'm not sure how useful they'll be, but if you're interested email me, and | I'll email the source. I haven't tested them, but it's pretty mechanical | code so I don't suspect any major problems and any should be relatively | straightforward to fix. See `Dealing with Large Bananas` for the concept | (and for documentation, as it has no documentation yet). | | _________________________________________________________________ | STOP MORE SPAM with the new MSN 8 and get 2 months FREE* | http://join.msn.com/?page=features/junkmail | | _______________________________________________ | template-haskell mailing list | template-haskell@haskell.org | http://www.haskell.org/mailman/listinfo/template-haskell