[GHC] #13311: Audit shady uses of tcSplitSigmaTy

[GHC]

#13311: Audit shady uses of tcSplitSigmaTy
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        Reporter:  RyanGlScott       |                Owner:  RyanGlScott
            Type:  task              |               Status:  new
        Priority:  normal            |            Milestone:  8.4.1
       Component:  Compiler (Type    |              Version:  8.1
  checker)                           |
      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 goldfire):

 Replying to [comment:3 RyanGlScott]:
 >   When you type this into GHCi:
 >
 >   {{{
 >   λ> let a :: forall a b. (Num a, Num b) => (# a, b #); !a = (# 1, 2 #)
 >   }}}
 >
 >   you get this error:
 >
 >   {{{
 >   You can't mix polymorphic and unlifted bindings
 >     !a = (# 1, 2 #)
 >     Probable fix: add a type signature
 >   }}}

 I'm confused. That's not an unlifted binding!

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13311#comment:4>
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