[GHC] #9858: Typeable instances should be kind-aware

[GHC]

#9858: Typeable instances should be kind-aware
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        Reporter:  dreixel           |                   Owner:
            Type:  bug               |                  Status:  new
        Priority:  highest           |               Milestone:  7.10.1
       Component:  Compiler          |                 Version:  7.9
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  None/Unknown      |  Unknown/Multiple
      Blocked By:                    |               Test Case:
 Related Tickets:                    |                Blocking:
                                     |  Differential Revisions:
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Comment (by hvr):

 Replying to [comment:64 rwbarton]:
 > Abstractly my main concern is that we've made a change (implicitly
 deriving Typeable everywhere) for the wrong reasons, and concretely my
 main fear, given the timing of this change, is that we'll find the new
 approach is untenable for some reason or other and be forced back into a
 world in which explicit deriving Typeable is required.

 Does artificially keeping require to explicitly derive `Typeable` during
 the 7.10 cycle actually help us identifying issues, rather than just
 releasing this into the wild with 7.10 and gather real-world data during
 7.10's life-cycle?

 Fwiw, IIRC we wanted to turn on `AutoDeriveTypeable` by default anyway
 sooner or later. So this change just accomplishes that by a different
 mechanism, but the outcome is the same IMO.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9858#comment:66>
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