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

[GHC]

#9858: Typeable instances should be kind-aware
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        Reporter:  dreixel           |                   Owner:  dreixel
            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 crockeea):

 Replying to [comment:21 goldfire]:
 > I will point out one drawback: I believe users will be confused about
 the need for `Typeable` constraints. After all, if ''every'' type is
 `Typeable`, then why include the constraint? We cognoscenti know that the
 `Typeable` constraint is just implicitly passing the runtime witness, but
 we'll have to be careful to explain this to those who think that class
 constraints are all about logical statements, not implicit type-determined
 parameters.

 After using Haskell for several years, that ''still'' trips me up. If you
 are able to make everything `Typeable`, might there be a way to make the
 `Typeable` constraint implicit, at least when it's needed?

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9858#comment:22>
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