[GHC] #12709: GHC panic

[GHC]

#12709: GHC panic
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        Reporter:  Iceland_jack      |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.1
      Resolution:                    |             Keywords:
                                     |  LevityPolymorphism
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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Changes (by simonpj):

 * keywords:   => LevityPolymorphism


Comment:

 We should rejec
 {{{
 a :: BoxUnbox
 a = let u :: Num (a :: TYPE rep) => a
         u = 1 + 2 + 3 + 4
 }}}
 because application `1 + blah` has a levity-polymorphic argument.  See the
 paper.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12709#comment:4>
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