[GHC] #9242: Implement {-# OVERLAPPABLE #-} and {-# INCOHERENT #-} pragmas

[GHC]

#9242: Implement {-# OVERLAPPABLE #-} and {-# INCOHERENT #-} pragmas
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        Reporter:  simonpj           |            Owner:  diatchki
            Type:  feature request   |           Status:  new
        Priority:  normal            |        Milestone:
       Component:  Compiler          |          Version:  7.8.2
      Resolution:                    |         Keywords:
Operating System:  Unknown/Multiple  |     Architecture:  Unknown/Multiple
 Type of failure:  None/Unknown      |       Difficulty:  Unknown
       Test Case:                    |       Blocked By:
        Blocking:                    |  Related Tickets:
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Comment (by diatchki):

 I like the OVERLAPPING and OVERLAPPABLE idea, and I was going to have a
 stab at implementing it.   I just thought it'd be easier to start by
 simply exposing what GHC does first, before changing more things.  So,
 this, and updating the manual is on my TODO list.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9242#comment:11>
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