[GHC] #1123: forall not hoisted properly

[GHC]

#1123: forall not hoisted properly
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 Reporter:  Ashley Yakeley <ashley at semantic.org>  |          Owner:         
     Type:  bug                                   |         Status:  new    
 Priority:  normal                                |      Milestone:         
Component:  Compiler                              |        Version:  6.6    
 Severity:  normal                                |     Resolution:         
 Keywords:                                        |     Difficulty:  Unknown
 Testcase:                                        |   Architecture:  Unknown
       Os:  Unknown                               |  
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Comment (by simonpj):

 Good program.   I believe this is another place where the quest for
 impredicativity has led me to make GHC's behaviour worse for ordinary
 predicative programs.  This particular program is, I believe, rejected by
 the rules of our paper "Boxy types: inference for ...".

 It's very helpful having examples like these to guide thinking.  I wonder
 if anyone actually uses impredicativity.  It carries heavier costs than
 I'd anticipated.

 Simon

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/1123>
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