[GHC] #2439: Missed optimisation with dictionaries and loops

[GHC]

#2439: Missed optimisation with dictionaries and loops
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    Reporter:  rl                |       Owner:  simonpj                
        Type:  bug               |      Status:  new                    
    Priority:  lowest            |   Milestone:  7.6.2                  
   Component:  Compiler          |     Version:  6.9                    
    Keywords:                    |          Os:  Unknown/Multiple       
Architecture:  Unknown/Multiple  |     Failure:  Runtime performance bug
  Difficulty:  Unknown           |    Testcase:                         
   Blockedby:                    |    Blocking:                         
     Related:                    |  
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Changes (by carter):

 * cc: carter.schonwald@… (added)


Comment:

 @simon
 changing the single method type class encoding would break edwardk's
 reflection library http://hackage.haskell.org/package/reflection (which
 exploits that newtype encoding for single method type classes)

 Is there a natural example where forcing that single method to whnf (if
 you mean that form of strictness) would be bad?

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2439#comment:18>
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