[GHC] #7880: Require "forall" in definitions of polymorphic types

[GHC]

#7880: Require "forall" in definitions of polymorphic types
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    Reporter:  monoidal          |       Owner:                             
        Type:  bug               |      Status:  new                        
    Priority:  normal            |   Milestone:                             
   Component:  Compiler          |     Version:  7.6.3                      
    Keywords:                    |          Os:  Unknown/Multiple           
Architecture:  Unknown/Multiple  |     Failure:  GHC accepts invalid program
  Difficulty:  Unknown           |    Testcase:                             
   Blockedby:                    |    Blocking:                             
     Related:                    |  
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Comment(by simonpj):

 That is true but seems horribly ad hoc.  It would be simpler and more
 uniform just to say that "=>" doesn't trigger an implicit quantification
 point.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7880#comment:5>
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