[GHC] #8560: undeducable Typeable error with data kinds when deriving Data for GADT in GHC version 7.7.20131122

[GHC]

#8560: undeducable Typeable error with data kinds when deriving Data for GADT in
GHC version 7.7.20131122
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       Reporter:  carter            |             Owner:
           Type:  bug               |            Status:  new
       Priority:  normal            |         Milestone:
      Component:  Compiler          |           Version:  7.7
       Keywords:                    |  Operating System:  Unknown/Multiple
   Architecture:  Unknown/Multiple  |   Type of failure:  None/Unknown
     Difficulty:  Unknown           |         Test Case:
     Blocked By:                    |          Blocking:
Related Tickets:                    |
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 This may be an artifact of  issue #8128 (see
 https://ghc.haskell.org/trac/ghc/ticket/8128#comment:5), but I'm seeing
 examples involving data kinds where Typeable isn't deducible.  This could
 be an artifact of other problems, BUT since with 7.7 onwards, we have
 baked in polykinded Typeable, things should always "just work™" right?

 the error with current head is as follows (and i'm attaching the code +
 current finger print too)

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8560>
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