[GHC] #2440: Bad code with type families

[GHC]

#2440: Bad code with type families
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    Reporter:  rl                        |        Owner:                  
        Type:  run-time performance bug  |       Status:  new             
    Priority:  normal                    |    Milestone:  6.10 branch     
   Component:  Compiler                  |      Version:  6.9             
    Severity:  normal                    |   Resolution:                  
    Keywords:                            |   Difficulty:  Unknown         
    Testcase:                            |           Os:  Unknown/Multiple
Architecture:  Unknown/Multiple          |  
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Comment (by chak):

 Replying to [comment:7 batterseapower]:
 > (Repost for formatting reasons...)
 >
 > Is there some reason the coercion for this case is so complicated? It
 seems to me (with my admittedly limited knowledge of type coercions) that
 we could improve it to:

 You are right that coercions sometimes get overly complicated.  That is
 often due to shortcomings of the representation used when generating these
 coercions.  We would like to fix that, but so far haven't settled on
 exactly how (and also like to avoid rearranging the source in many
 places).

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2440#comment:8>
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