[GHC] #11120: Missing type representations

[GHC]

#11120: Missing type representations
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        Reporter:  goldfire          |                Owner:
            Type:  bug               |               Status:  new
        Priority:  high              |            Milestone:  8.0.1
       Component:  Compiler          |              Version:  7.11
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by bgamari):

 It seems like this might be worth trying to fix for 8.0.

 > Perhaps I'm being dense, but why is this problematic? What panic or
 other undesirable situation will arise? To be clear: I'm proposing to keep
 `TyCon` and `Module` and such in `GHC.Types`. But also to put the
 representations for things defined in `GHC.Types` in `GHC.Types`.

 I can't think of any reason why this should be tricky. Simon, perhaps you
 could elaborate on the reasons for this being so tricky?

 > But isn't the fingerprint Very Important? As in: don't we rely
 critically on fingerprints being unique when doing type comparison? If I
 understand this correctly, the current implementation means that
 `-dsuppress-uniques` makes the whole Typeable story unsound. And
 `-dsuppress-uniques` is meant to be a pretty-printing flag.

 Indeed this is quite an unexpected effect for what ought to be a debugging
 flag. I've opened Phab:D1629 replacing the bogus fingerprint logic with a
 testsuite normaliser.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11120#comment:4>
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