mutiparameter classes problem
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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