[GHC] #14199: Document Type.Reflection better (Fun and Con')

[GHC]

#14199: Document Type.Reflection better (Fun and Con')
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        Reporter:  dfeuer            |                Owner:  bgamari
            Type:  bug               |               Status:  merge
        Priority:  high              |            Milestone:  8.2.2
       Component:  Core Libraries    |              Version:  8.2.1
      Resolution:                    |             Keywords:  Typeable
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Documentation     |  Unknown/Multiple
  bug                                |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D3943
       Wiki Page:                    |
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Comment (by dfeuer):

 I think it would be helpful to explain, in the documentation of `Con'` and
 `App`, just what separates the variables that can be separated with `App`
 from the ones that can be separated with `Con'`. For example, given

 {{{#!hs
 data Foo j k (l :: j -> k)
 }}}

 one might naively expect something like `App (App (App (Con Foo) Bool)
 Type) SBool`, but that is not so. Going into a bit more detail about that
 would be helpful, and it might even be worth mentioning ''why'' the naive
 guess is wrong.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14199#comment:6>
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