[GHC] #13409: Data types with higher-rank kinds are pretty-printed strangely

10 Mar 2017

      #13409: Data types with higher-rank kinds are pretty-printed strangely
-------------------------------------+-------------------------------------
           Reporter:  RyanGlScott    |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.0.2
  (Type checker)                     |
           Keywords:  TypeInType     |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:  #13399
Differential Rev(s):                 |         Wiki Page:
-------------------------------------+-------------------------------------
 First observed in https://ghc.haskell.org/trac/ghc/ticket/13399#comment:5.
 If you define this:

 {{{#!hs
 data Foo :: (* -> *) -> (forall k. k -> *)
 }}}

 and type `:i Foo` into GHCi, you get this back:

 {{{
 type role Foo phantom nominal phantom
 data Foo (a :: * -> *) k (c :: k)
 }}}

 This seems to imply that Foo has three visible type parameters, which
 isn't true at all!

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Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13409
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