[GHC] #8813: further support deriving instances Typeable1, Typeable2, etc

[GHC]

#8813: further support deriving instances Typeable1, Typeable2, etc
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        Reporter:  maeder                     |            Owner:
            Type:  task                       |           Status:  new
        Priority:  normal                     |        Milestone:
       Component:  Compiler                   |          Version:
      Resolution:                             |  7.8.1-rc1
Operating System:  Unknown/Multiple           |         Keywords:
 Type of failure:  GHC rejects valid program  |     Architecture:
       Test Case:                             |  Unknown/Multiple
        Blocking:                             |       Difficulty:  Unknown
                                              |       Blocked By:
                                              |  Related Tickets:
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Comment (by simonpj):

 Guys, lets all be polite!

 Christian, yes indeed one of the primary motivations for
 `-XConstraintKinds` was to allow "type" synonyms to include class
 constraints (and indeed all sorts of constraints).

 Pedro said "I couldn't find an acceptable solution. But, as I said before,
 I would very much welcome a better solution."  Reid suggested one, perhaps
 one that Pedro thought of and discarded, perhaps not.  It has the
 advantage that it might be a simple change to `Data.Typeable` making
 (deprecated) exports of `Typeable1`, `Typeable2` etc.

 Pedro: can you think of any problems with this?  Thanks Reid.

 If someone would like to try it out and send a patch the validates, it
 might just make it into 7.8.

 Simon

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8813#comment:15>
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