[GHC] #14160: Type inference breaking change in GHC 8.0.2

[GHC]

#14160: Type inference breaking change in GHC 8.0.2
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        Reporter:  Iceland_jack      |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.2.1
      Resolution:                    |             Keywords:
                                     |  ImpredicativeTypes
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):

 Agreed that this is an "improvement" (as in, GHC is behaving closer to
 spec) from previous behavior.

 Yes to allowing polytypes in visible type arguments.

 No to accepting `g = undefined`. It's impredicative! :)

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14160#comment:3>
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