bug neither fixed nor listed as known

[Sigbjorn Finne]

Hi,

he's just being overly modest not to relay the good news
himself, but one Sir Jeffrey Lewis has just committed a TC
change which fixes this. Thanks for reporting it.

--sigbjorn

----- Original Message ----- 
From: "Ralf Laemmel" <Ralf.Laemmel@cwi.nl>
To: <hugs-bugs@haskell.org>
Sent: Wednesday, March 06, 2002 07:49
Subject: bug neither fixed nor listed as known


> Dear Hugs-Bugsers,
> 
> As reported in Sep. last year,
> there is very serious problem
> in hugs when it comes to class
> hierarchies. See the program
> below. Is anyone maintaining 
> hugs and paying attention to 
> incoming bug reports?
> 
> Thanks,
> Ralf
> 
> import Monad
> 
> class Monad m => C1 m x
> 
> -- Monad m is implied by C1 but test diverges if constraint not present
> class (C1 m x) => C2 m x
>   where
>     c2 :: x -> m x
> 
> instance Monad m => C1 m Bool
> instance C2 Maybe Bool
>   where
>     c2 = return
> 
> test :: Maybe Bool
> test = c2 True
> 
> 
> 
> -- 
> Dr.-Ing. Ralf Laemmel
> CWI & VU, Amsterdam, The Netherlands
> http://www.cwi.nl/~ralf/
> http://www.cs.vu.nl/~ralf/