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 |
|
