[Haskell-cafe] Noticed this change about infix decls in GHC 7.4.2
chrisdone at googlemail.com
Sun Jun 17 20:53:47 CEST 2012
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
(++) :: Monoid a => a -> a -> a
(++) = mappend
infixr 5 ++
This compiles happily on GHC 6.12.3, but on 7.4.2 says:
Ambiguous occurrence `++'
It could refer to either `Data.Monoid.Operator.++',
defined at src/Data/Monoid/Operator.hs:8:1
imported from `Prelude' at
(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
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.
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.
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