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mutiparameter classes problem

    • Closed Issue created by nobody @trac-nobody 
    hello,
i have run into something that looks like a bug in ghc 6.0.
here is an example:

> module A where
> class C a b where f :: a -> b
> g x = fst (f x)

for this program hugs reports that "g" has an ambiguous
type:
  C a (b,c) => a -> b
which seems reasonable.
however ghc does not report an error, and infers the
following type:
  C a (b, ()) => a -> b
(i have changed the formatting for easier comparing).
it seems that somehow the second component of the tuple
became (),
but i don't see why.

bye
iavor
    Trac metadata
    Trac field Value
    Version 6.0
    Type Bug
    TypeOfFailure OtherFailure
    Priority normal
    Resolution ResolvedFixed
    Component Compiler (Type checker)
    Test case
    Differential revisions
    BlockedBy
    Related
    Blocking
    CC
    Operating system
    Architecture
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