[GHC] #9858: Typeable instances should be kind-aware

[GHC]

#9858: Typeable instances should be kind-aware
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        Reporter:  dreixel           |                   Owner:
            Type:  bug               |                  Status:  new
        Priority:  highest           |               Milestone:  7.12.1
       Component:  Compiler          |                 Version:  7.9
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  None/Unknown      |  Unknown/Multiple
      Blocked By:                    |               Test Case:
 Related Tickets:                    |                Blocking:
                                     |  Differential Revisions:  Phab:D652
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Comment (by oerjan):

 Replying to [comment:77 diatchki]:
 > Hm, I think I can see what might be the issue, in fact there might be 2:
 >   * {{{() :: *}}} and {{{() :: Constraint}}} will end up having the same
 representation
 >   * Have to look at how we compute type reps for odd rank-2 types like
 {{{ ((),()) => () }}}
 >
 > I'll have a go at a fix.

 Although the automatic currying makes it disappear in this particular
 example, tuples like `((),())` also get the same representation as `*` and
 `Constraint`. I guess you currently need the `()` case to build any
 others, but I'm not sure if that should be counted on.  (I also guess this
 all means Richard was right.)

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9858#comment:78>
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