[GHC] #11719: Cannot use higher-rank kinds with type families

[GHC]

#11719: Cannot use higher-rank kinds with type families
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        Reporter:  ocharles          |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.8.1
       Component:  Compiler (Type    |              Version:  8.0.1-rc2
  checker)                           |
      Resolution:                    |             Keywords:  TypeInType
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  GHC rejects       |            Test Case:
  valid program                      |  dependent/should_compile/T11719
      Blocked By:                    |             Blocking:
 Related Tickets:  #13913            |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by Iceland_jack):

 Something to consider (I don't know if I got the typing right, but
 allowing higher rank kinds in splitting type application)

 {{{#!hs
 type RudeWord a =
   forall xx. xx -> a

 type family
   Split (a :: res) :: forall arg. Maybe (RudeWord res, arg) where
   Split ((f :: RudeWord res) (a :: k)) = 'Just '(f, a)
   Split _                              = 'Nothing
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11719#comment:21>
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