[GHC] #14993: QuantifiedConstraints and principal types

[GHC]

#14993: QuantifiedConstraints and principal types
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        Reporter:  Iceland_jack      |                Owner:  (none)
            Type:  task              |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.5
      Resolution:                    |             Keywords:
                                     |  QuantifiedConstraints, wipT2893
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 AntC):

 I'd like to ask Simon a 'History of Haskell' type question while this
 development work is fresh in memory:

 The attention it gets in OutsideIn(X) shows the idea has stayed in the
 back of your mind since 2000. ghc's type inference engine gets radical
 surgery every half-decade or so.

 Did something happen that got `-XQuantifiedConstraints to a 'sweet
 spot'?/changed **4.2**'s evaluation as it being "not practical"? Or could
 it as easily have been developed in 2005 or 2010 or ...?

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14993#comment:6>
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