[GHC] #3698: Bad code generated for zip/filter/filter loop

[GHC]

#3698: Bad code generated for zip/filter/filter loop
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    Reporter:  rl                |       Owner:                         
        Type:  bug               |      Status:  new                    
    Priority:  normal            |   Milestone:                         
   Component:  Compiler          |     Version:  6.13                   
  Resolution:                    |    Keywords:                         
          Os:  Unknown/Multiple  |    Testcase:                         
Architecture:  Unknown/Multiple  |     Failure:  Runtime performance bug
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Comment (by rl):

 Hmm, yes, I guess it would be good to detect that, too. FWIW, essentially
 the same code is generated if we make `zip_filter` monomorphic:
 {{{
 zip_filter :: Double -> [Double] -> [Double] -> [Double]
 }}}
 Here, we know what `(<)` is so we don't have to detect this.

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Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3698#comment:2>
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