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

[GHC]

#8813: further support deriving instances Typeable1, Typeable2, etc
----------------------------------------------+----------------------------
        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:
----------------------------------------------+----------------------------

Comment (by kosmikus):

 I think that even if `TypeableN` would be added as `type` synonyms using
 `-XConstraintKinds`, they should be deprecated. They're ugly and don't add
 anything except (a limited amount of) backwards compatibility. Adding a
 kind-signature in a case that'd otherwise be "too" polymorphic is much
 clearer IMHO.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8813#comment:18>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler