Re: [GHC] #1241: Functional dependencies not checked.

[GHC]

#1241: Functional dependencies not checked.
-+--
 Reporter:  guest|  Owner: 
 Type:  bug  | Status:  new
 Priority:  normal   |  Milestone:  _|_
Component:  Compiler (Type checker)  |Version:  6.6
 Severity:  normal   | Resolution: 
 Keywords:   | Difficulty:  Unknown
 Testcase:   |   Architecture:  Unknown
   Os:  Unknown  |  
-+--
Comment (by guest):

 The problem is that the class instance {{{F Int b}}} vialotes the
 functional dependecy on {{{F}}} and, for this reason, it should be
 rejected.  This is similar to rejecting an instance {{{F Char Bool}}} when
 we already have an instance for {{{F Char Char}}} except that, in this
 case, the instance is conflicting with itself.

 Relaxing the coverage condition is OK but we still need to check that
 instances satisfy the functional dependecies of the class (just like we
 need to check that instances satisfy the super classes for a class).  I
 thought that GHC was supposed to use the dependecy rule (according to
 http://hackage.haskell.org/trac/haskell-prime/wiki/FunctionalDependencies)
 and I think that in 6.4 this used to work but, I guess, in 6.6 this check
 was removed?

 -Iavor

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Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/1241
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Re: [GHC] Visual Haskell install error

[Dennis van der Pool]

Hi Scott,

Did you already got it working? I got the same problem (with VS2005 though).

Dennis


Scott Brown-5 wrote:
 
 Hello,
   
   when I try to install Visual Haskell for Visual Studio 2003 I get the
 following errors:
   
   Failed to setup vs_haskell.dll
   Failed to setup vs_haskell_babel.dll
   Failed to setup vs_haskell_dlg.dll
   
   Is there a solution for this bug?
   
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