[GHC] #4426: Simplify the rules for implicit quantification

[GHC]

#4426: Simplify the rules for implicit quantification
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              Reporter:  simonpj     |            Owner:
                  Type:  feature     |           Status:  patch
  request                            |        Milestone:  7.10.1
              Priority:  low         |          Version:  6.12.3
             Component:  Compiler    |         Keywords:
            Resolution:              |     Architecture:  Unknown/Multiple
      Operating System:              |       Difficulty:  Unknown
  Unknown/Multiple                   |       Blocked By:
       Type of failure:              |  Related Tickets:  #7880
  None/Unknown                       |
             Test Case:              |
              Blocking:              |
Differential Revisions:  Phab:D211   |
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Comment (by Edward Z. Yang <ezyang@…>):

 In [changeset:"275dcafbfb6b371dd5d8943fa4df9c23e68f6165/ghc"]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="275dcafbfb6b371dd5d8943fa4df9c23e68f6165"
 Add -fwarn-context-quantification (#4426)

 Summary:
 This warning (enabled by default) reports places where a context
 implicitly binds a type variable, for example

 type T a = {-forall m.-} Monad m => a -> m a

 Also update Haddock submodule.

 Test Plan: validate

 Reviewers: hvr, goldfire, simonpj, austin

 Reviewed By: austin

 Subscribers: simonmar, ezyang, carter

 Differential Revision: https://phabricator.haskell.org/D211

 GHC Trac Issues: #4426
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4426#comment:15>
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