[GHC] #7224: Polymorphic kind annotations on type classes don't always work as expected

[GHC]

#7224: Polymorphic kind annotations on type classes don't always work as expected
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 Reporter:  slindley                   |          Owner:                         
     Type:  bug                        |         Status:  new                    
 Priority:  normal                     |      Component:  Compiler (Type checker)
  Version:  7.6.1-rc1                  |       Keywords:  kind polymorphism      
       Os:  Unknown/Multiple           |   Architecture:  Unknown/Multiple       
  Failure:  GHC rejects valid program  |       Testcase:                         
Blockedby:                             |       Blocking:                         
  Related:                             |  
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Comment(by slindley):

 If I'd actually switched on PolyKinds in ghci as well as the source file,
 then I'd have got:

 {{{
 *Main> :t ret
 ret :: PMonad k m => a -> m i i a
 *Main> :t ret'
 ret' :: PMonad' m => a -> m BOX BOX a
 }}}

 (The mysterious * disappears if {{{PolyKinds}}} is enabled.)

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7224#comment:1>
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