[GHC] #13603: Can't resolve levity polymorphic superclass

[GHC]

#13603: Can't resolve levity polymorphic superclass
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        Reporter:  Iceland_jack      |                Owner:  (none)
            Type:  bug               |               Status:  closed
        Priority:  normal            |            Milestone:  8.2.1
       Component:  Compiler          |              Version:  8.0.1
      Resolution:  fixed             |             Keywords:
                                     |  LevityPolymorphism, TypeInType
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
                                     |  typecheck/should_compile/T13603
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D3489
       Wiki Page:                    |
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Comment (by Iceland_jack):

 Out of curiosity, can any of those `TYPE rep` annotations be omitted in
 ''HEAD'' while retaining levity polymorphism?

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13603#comment:7>
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