[GHC] #9334: Implement "instance chains"

[GHC]

#9334: Implement "instance chains"
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              Reporter:  diatchki    |             Owner:  diatchki
                  Type:  feature     |            Status:  new
  request                            |         Milestone:
              Priority:  normal      |           Version:  7.9
             Component:  Compiler    |          Keywords:
  (Type checker)                     |  Operating System:  Unknown/Multiple
            Resolution:              |   Type of failure:  None/Unknown
Differential Revisions:              |         Test Case:
          Architecture:              |          Blocking:
  Unknown/Multiple                   |
            Difficulty:  Unknown     |
            Blocked By:              |
       Related Tickets:              |
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Comment (by simonpj):

 OK, by all means.  Honestly, I am not (yet) convinced that benefit is
 worth the extra complexity.  Do try to share code with the type-family
 apartness stuff; the paper on closed type families would be a good
 reference.

 Simon

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9334#comment:5>
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