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

[GHC]

#9858: Typeable instances should be kind-aware
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        Reporter:  dreixel           |                   Owner:  dreixel
            Type:  bug               |                  Status:  new
        Priority:  highest           |               Milestone:  7.10.1
       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:
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Comment (by int-e):

 Replying to [comment:26 int-e]:
 > I'm afraid there is no good interim solution here. I favor spj's
 suggestion, but #9111 suggests that some people actually use
 {{{Typeable}}} for {{{Proxy}}}.

 I've changed my mind about SPJ's idea. It's very late in the ghc-7.10
 release cycle, and the design of the long-term solution is still in flux,
 so any ''drastic'' stop-gap measure bears a significant risk of breaking
 users' code twice. And there are quite a lot of users, not least because
 `Typeable` is poly-kinded (see also Edward's comment:37 which carries some
 weight).

 I'd rather see this bug documented and communicated prominently so that
 everybody who runs untrusted Haskell code knows about it, and take further
 measures to sandbox that code. (This is a good idea anyway; ghc, its RTS
 and the libraries are really too big to be trusted even with `SafeHaskell`
 enabled.)

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9858#comment:40>
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