[GHC] #12670: Representation polymorphism validity check is too strict

[GHC]

#12670: Representation polymorphism validity check is too strict
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        Reporter:  bgamari           |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.2.1
       Component:  Compiler (Type    |              Version:  8.0.1
  checker)                           |
      Resolution:                    |             Keywords:  typeable
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by goldfire):

 Replying to [comment:13 simonpj]:
 > Let's see what Richard has to say.

 I say "yes".

 I also say that your `Fun` is quite wrong. I prefer this one:

 {{{#!hs
 pattern Fun
   :: forall k (a_to_b :: k). ()
   => forall r r' (a :: TYPE r) (b :: TYPE r'). (k ~ Type, a_to_b ~ (a ->
 b))
   => TypeRep a -> TypeRep b -> TypeRep a_to_b
 }}}

 But otherwise I agree with your conclusions.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12670#comment:14>
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