[GHC] #7436: Derived Foldable and Traversable instances become extremely inefficient due to eta-expansion

[GHC]

#7436: Derived Foldable and Traversable instances become extremely inefficient due
to eta-expansion
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    Reporter:  shachaf           |       Owner:                         
        Type:  bug               |      Status:  new                    
    Priority:  normal            |   Milestone:                         
   Component:  Compiler          |     Version:  7.6.1                  
    Keywords:                    |          Os:  Unknown/Multiple       
Architecture:  Unknown/Multiple  |     Failure:  Runtime performance bug
  Difficulty:  Unknown           |    Testcase:                         
   Blockedby:                    |    Blocking:                         
     Related:                    |  
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Comment(by simonpj):

 Thanks for the simple version.  Truly bizarre.  The slow code allocate
 ONLY 11 MBYTE, and yet takes EIGHT SECONDS to run.  No time to look today,
 but if anyone cares to investigate that'd be great.  (One thing to try
 would be profiling, though that might make the bug disappear.)

 Simon

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7436#comment:4>
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