[GHC] #8090: MetaKinds - PolyKinds generalization

[GHC]

#8090: MetaKinds - PolyKinds generalization
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        Reporter:  wvv               |            Owner:
            Type:  feature request   |           Status:  new
        Priority:  normal            |        Milestone:
       Component:  Compiler          |          Version:  7.6.3
      Resolution:                    |         Keywords:
Operating System:  Unknown/Multiple  |     Architecture:  Unknown/Multiple
 Type of failure:  None/Unknown      |       Difficulty:  Unknown
       Test Case:                    |       Blocked By:
        Blocking:                    |  Related Tickets:
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Comment (by wvv):

 1) This is a part of lambda-cube.
 {{{
 Agda  Haskell
 Set0  a::*
 Set1  a::k  <<==>> a :: (k :: *)
 Set2  a :: (k2 :: (k :: *))
 ...
 }}}


 2) rankNkinds is essential to work with rank(N-1)kinds: classes and
 (G)ADTs.

 We already have a lot of rank2kinds(PolyKinds), so we already need to have
 rank3kinds.

 Developers said they did new Typeable in GHC 7.8, but it is impossible to
 write

 {{{
 data Foo (a::(b::k)->*) deriving Typeable
 }}}

 new Typeable = Typeable2kinds; but Foo is a part of Typeable3kinds

 3) I think for several years max rank kind = 7 is enough (Bill Gates said
 "640K ought to be enough for anybody")

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8090#comment:3>
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