[GHC] #8477: Allow inferring ambiguous types

[GHC]

#8477: Allow inferring ambiguous types
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        Reporter:  aavogt            |            Owner:
            Type:  feature request   |           Status:  new
        Priority:  normal            |        Milestone:
       Component:  Compiler          |          Version:  7.6.3
      Resolution:                    |         Keywords:
Operating System:  Unknown/Multiple  |     Architecture:  Unknown/Multiple
 Type of failure:  None/Unknown      |       Difficulty:  Unknown
       Test Case:                    |       Blocked By:
        Blocking:                    |  Related Tickets:  8390
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Comment (by aavogt):

 I am asking for more than -XAllowAmbiguousTypes. I think it could be
 possible to have ghc accept the request.hs without having to write a type
 signature (which in turn needs -XAllowAmbiguousTypes and
 -XScopedTypeVariables).

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8477#comment:2>
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