#5499: Tagging constructors with record/product phantom type
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    Reporter:  basvandijk         |        Owner:              
        Type:  feature request    |       Status:  new         
    Priority:  normal             |    Milestone:              
   Component:  libraries (other)  |      Version:  7.2.1       
    Keywords:                     |     Testcase:              
   Blockedby:                     |   Difficulty:              
          Os:  Unknown/Multiple   |     Blocking:              
Architecture:  Unknown/Multiple   |      Failure:  None/Unknown
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Comment(by dreixel):

 Replying to [comment:7 basvandijk]:
 > Secondly I see a problem where `GToJSON`
 
[https://github.com/basvandijk/aeson/blob/5bdf30ed4b32f2cc169f6e4e58d1688bcb02c197/Data/Aeson/Types/Internal.hs#L336
 is used]. If `GToJSON` had an extra `b` parameter which value does it get
 in:
 >
 {{{
 class ToJSON a where
     toJSON   :: a -> Value

     default toJSON :: (Generic a, GToJSON (Rep a)) => a -> Value
     toJSON = gToJSON . from
 }}}

 I *think* that a fresh type variable will do fine at that point.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5499#comment:8>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler

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