[GHC] #2456: For higher kinds, instance declarations need quantification in the context

[GHC]

#2456: For higher kinds, instance declarations need quantification in the context
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  Reporter:  ronwalf           |          Owner:         
      Type:  feature request   |         Status:  new    
  Priority:  normal            |      Milestone:  _|_    
 Component:  Compiler          |        Version:  6.9    
Resolution:                    |       Keywords:         
        Os:  Unknown/Multiple  |   Architecture:  x86    
   Failure:  None/Unknown      |     Difficulty:  Unknown
  Testcase:                    |      Blockedby:         
  Blocking:                    |        Related:         
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Comment(by goldfire):

 In response to the type system question: Essentially, yes, if something is
 expressible in FC, then it must* be good. But, I know of two loopholes in
 FC: unsafe coercions (we all knew that), and the
 !GeneralizedNewtypeDeriving bug (see #1496, #4846, which seem, to me, to
 be duplicates).

 *FC is a complicated beast these days, and though we've proved it type-
 safe in theory, we can't be sure in practice. :)

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2456#comment:9>
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