Yes, it's a bug. Happily a dup of http://hackage.haskell.org/trac/ghc/ticket/6120, which is already fixed. I'll add your program as a regression test though. Thanks for reporting Simon | -----Original Message----- | From: haskell-cafe-bounces@haskell.org [mailto:haskell-cafe- | bounces@haskell.org] On Behalf Of Christopher Done | Sent: 17 June 2012 19:54 | To: Haskell Cafe | Subject: [Haskell-cafe] Noticed this change about infix decls in GHC 7.4.2 | | So I have some module, in a work project that I'm portnig from GHC | 6.12.3 to GHC 7.4.2, | | module Data.Monoid.Operator where | | import Data.Monoid | | (++) :: Monoid a => a -> a -> a | (++) = mappend | infixr 5 ++ | | This compiles happily on GHC 6.12.3, but on 7.4.2 says: | | src/Data/Monoid/Operator.hs:9:10: | Ambiguous occurrence `++' | It could refer to either `Data.Monoid.Operator.++', | defined at src/Data/Monoid/Operator.hs:8:1 | or `Prelude.++', | imported from `Prelude' at | src/Data/Monoid/Operator.hs:3:8-27 | (and originally defined in `GHC.Base') | | It seems that it used to assign higher priority to the declared thing | in the current module over the imported one. Is this intentional? I'd | suspect not, given that if I comment the binding out: | | -- (++) :: Monoid a => a -> a -> a | -- (++) = mappend | | I get: | | src/Data/Monoid/Operator.hs:9:10: | The fixity signature for `++' lacks an accompanying binding | (The fixity signature must be given where `++' is declared) | | Which seems to contradict the previous error message. | | Bug? | | Ciao! | | P.S. Yes, I know I can fix this by not importing Prelude. | P.P.S Yes, I know there's a <> or <+> defined now, but I prefer (++), thanks. | | _______________________________________________ | Haskell-Cafe mailing list | Haskell-Cafe@haskell.org | http://www.haskell.org/mailman/listinfo/haskell-cafe