[GHC] #10343: Make Typeable track kind information better

[GHC]

#10343: Make Typeable track kind information better
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        Reporter:  oerjan            |                   Owner:
            Type:  feature request   |                  Status:  new
        Priority:  normal            |               Milestone:
       Component:  Compiler          |                 Version:  7.10.1
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  None/Unknown      |  Unknown/Multiple
      Blocked By:                    |               Test Case:  typeOf ::
 Related Tickets:  #9858             |  Typeable (a::k) => Proxy a ->
                                     |  TypeRep
                                     |                Blocking:
                                     |  Differential Revisions:
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Comment (by goldfire):

 Replying to [comment:5 simonpj]:
 > I'm assuming that much of what Oerjan wants will "just work" once we
 have Richard's kind equalities.  Right Richard?
 >
 > But not, perhaps, `kindRep` which I do not fully understand.

 I'm not sure exactly what "much of what Oerjan wants" refers to, so I
 can't make a claim one way or the other. I can say that the feature
 requested in this ticket will ''not'' just work in my branch.

 The problem is that if we have a `TypeRep` for some time `a` of kind `k`,
 there is no way, at runtime, to extract a `TypeRep` for `k`. `TypeRep`s
 simply don't store enough information to do this. Fixing this should be
 straightforward, and I believe is totally orthogonal to anything dealing
 with my branch. (Well, not ''totally'' orthogonal, because in my branch
 `kindRep (kindRep <<anything>>)` is a `TypeRep` for `*`, and today it
 would be a `TypeRep` for `BOX`. But this matters little.) Coming up with
 an API design is a touch harder, but I don't think it should be too bad,
 and it remains independent from the `TTypeRep a` story.

 Oerjan, you're a (the?) client of all this. Propose an API design. :)

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10343#comment:6>
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