[GHC] #8084: Enabling PolyKinds makes some type errors weird

[GHC]

#8084: Enabling PolyKinds makes some type errors weird
--------------------------------------------+------------------------------
        Reporter:  MartijnVanSteenbergen    |            Owner:
            Type:  bug                      |           Status:  new
        Priority:  normal                   |        Milestone:
       Component:  Compiler (Type checker)  |          Version:  7.6.3
      Resolution:                           |         Keywords:
Operating System:  Unknown/Multiple         |     Architecture:
 Type of failure:  None/Unknown             |  Unknown/Multiple
       Test Case:                           |       Difficulty:  Unknown
        Blocking:                           |       Blocked By:
                                            |  Related Tickets:
--------------------------------------------+------------------------------

Comment (by simonpj):

 I'd be interested to know what people think.

  * Should GHC display kind arguments by default (as now) or only with an
 explicit flag?  One dificulty with the latter is that an explicit flag is
 not very discoverable.  And if kind arguments are not displayed by default
 you might get messages like `Cannot unify X with X`, which looks like a
 bug, whereas `Cannot unify (X *) with (X (*->*))` makes more sense.

  * Should there be syntax to distinguish kind arguments?  e.g.  `(Any {*}
 Y)`, or `(Any @* Y)`.

 There are no major issues of principle here, just ones of design.

 Simon

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8084#comment:2>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler