[GHC] #15334: (forall x. c x, forall x. d x) is not equivalent to forall x. (c x, d x)

[GHC]

#15334: (forall x. c x, forall x. d x) is not equivalent to forall x. (c x, d x)
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        Reporter:  RyanGlScott       |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.6.1
       Component:  Compiler (Type    |              Version:  8.5
  checker)                           |             Keywords:
      Resolution:                    |  QuantifiedConstraints
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  GHC rejects       |  Unknown/Multiple
  valid program                      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by simonpj):

 > I would expect forall a b. (C a, D a b) to be shorthand for forall a b.
 C a and forall a b. D a b

 I agree that there is no other sensible interpretation, but it's a pretty
 significant implicit rewriting of types.  I'm not yet convinced that it
 pays its way.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15334#comment:8>
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