[GHC] #2595: Implement record update for existential and GADT data types

[GHC]

#2595: Implement record update for existential and GADT data types
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  Reporter:  simonpj          |          Owner:                  
      Type:  feature request  |         Status:  new             
  Priority:  normal           |      Milestone:  6.12 branch     
 Component:  Compiler         |        Version:  6.8.3           
Resolution:                   |       Keywords:                  
  Testcase:  tc244            |      Blockedby:                  
Difficulty:  Unknown          |             Os:  Unknown/Multiple
  Blocking:                   |   Architecture:  Unknown/Multiple
   Failure:  None/Unknown     |  
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Changes (by rampion):

 * cc: noah.easterly@… (added)
  * failure:  => None/Unknown
  * status:  closed => new
  * resolution:  fixed =>


Comment:

 Could this be extended to allow updating the non-universally-quantified
 type variables of the data constructor?  The example code still gives the
 error:

     Record update for insufficiently polymorphic field: foo :: a -> a
     In the expression: rec {foo = id}
     In the definition of `f': f rec = rec {foo = id}

 And it'd be nice to be able to update the existentials.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2595#comment:4>
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