[GHC] #14887: Explicitly quantifying a kind variable causes a telescope to fail to kind-check

[GHC]

#14887: Explicitly quantifying a kind variable causes a telescope to fail to kind-
check
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        Reporter:  RyanGlScott       |                Owner:  goldfire
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.8.1
       Component:  Compiler (Type    |              Version:  8.2.2
  checker)                           |
      Resolution:                    |             Keywords:  TypeInType
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  GHC rejects       |  Unknown/Multiple
  valid program                      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by simonpj):

 Principle: implicitly-quantified variables always precede explicitly-
 quantified variables in a type or kind.  So `Foo1` and `Foo2` in the OP
 are ''not'' equivalent.

 * In `Foo1` the implicitly-quantified variables are `k` and `a::k`; and
 GHC can put them in that order.
 * But in `Foo2` the implicitly quantified variable is only `a::k` and that
 can't come first.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14887#comment:10>
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