[GHC] #4191: Replace -fstrict-dicts with programmer-custom strictness annotations for class contexts

[GHC]

#4191: Replace -fstrict-dicts with programmer-custom strictness annotations for
class contexts
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    Reporter:  LouisWasserman    |        Owner:              
        Type:  feature request   |       Status:  new         
    Priority:  normal            |    Milestone:              
   Component:  Compiler          |      Version:  6.12.3      
    Keywords:                    |   Difficulty:              
          Os:  Unknown/Multiple  |     Testcase:              
Architecture:  Unknown/Multiple  |      Failure:  None/Unknown
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Comment(by rl):

 Strict dictionaries won't help with this in the head which uses selectors
 rather than `case` for method calls. Floating method selectors out of
 loops is not straightforward with the new rule-based method selection
 mechanism but is definitely something that should be looked into. Just
 making dictionaries strict is not enough, though.

 In 6.12, on the other hand, this is usually handled by !LiberateCase which
 isn't ideal but gets the job done. Are you compiling with -O2?

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4191#comment:12>
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