[GHC] #10592: Allow cycles in class declarations

[GHC]

#10592: Allow cycles in class declarations
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        Reporter:  MikeIzbicki       |                   Owner:
            Type:  feature request   |                  Status:  new
        Priority:  normal            |               Milestone:
       Component:  Compiler (Type    |                 Version:  7.10.1
  checker)                           |                Keywords:
      Resolution:                    |            Architecture:
Operating System:  Unknown/Multiple  |  Unknown/Multiple
 Type of failure:  None/Unknown      |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:                    |  Differential Revisions:
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Comment (by MikeIzbicki):

 My current implementation has constraints that look exactly like this,
 plus a lot more related to other aspects of the class hierarchy.  So
 supporting this would be a necessary condition for me cyclic class
 declarations for me, but I can't say for sure if it would be sufficient
 (but my guess is probably).

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10592#comment:7>
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