[GHC] #9200: Milner-Mycroft failure at the kind level

[GHC]

#9200: Milner-Mycroft failure at the kind level
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        Reporter:  ekmett                     |            Owner:
            Type:  bug                        |           Status:  new
        Priority:  normal                     |        Milestone:
       Component:  Compiler (Type checker)    |          Version:  7.8.2
      Resolution:                             |         Keywords:
Operating System:  Unknown/Multiple           |     Architecture:
 Type of failure:  GHC rejects valid program  |  Unknown/Multiple
       Test Case:                             |       Difficulty:  Unknown
        Blocking:                             |       Blocked By:
                                              |  Related Tickets:
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Comment (by simonpj):

 OK, so (NEWCUSK) is precisely (BASELINE) with a slightly expanded
 definition of CUSK (c.f. the
 [http://www.haskell.org/ghc/docs/latest/html/users_guide/kind-
 polymorphism.html#complete-kind-signatures current definition in the user
 manual]).  I'm all for that; I quite liked (BASELINE): it's pretty simple
 and lines up precisely with the term-level story (a la Mark Jones).

 Just to check, though, let's be sure we agree:
 {{{
 data T1 f a = MkT1 (f a)
 -- No CUSK
 -- Gets T1 :: forall k. (k->*) -> k -> *
 -- The generalisation takes place in the third bullet of step 3 of
 (BASELINE)

 data T2 a b :: *    -- Presumably a nullary data type
 -- No CUSK
 -- Gets T2 :: forall k1 k2. k1 -> k2 -> *
 -- Very similar to T1
 }}}

 I have no idea what you mean by "2) Allow more flexible partial kind
 signatures" in comment:19.

 Could you update the wiki page with:

  * (NEWCUSK) (= (BASELINE) + revised defn of CUSK)
  * the typing rules for closed type families

 Thanks!

 Simon

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9200#comment:21>
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