[GHC] #7543: Constraint synonym instances

[GHC]

#7543: Constraint synonym instances
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        Reporter:  monoidal          |                   Owner:
            Type:  bug               |                  Status:  new
        Priority:  normal            |               Milestone:  7.12.1
       Component:  Compiler          |                 Version:  7.6.1
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  None/Unknown      |  Unknown/Multiple
      Blocked By:                    |               Test Case:
 Related Tickets:                    |                Blocking:
                                     |  Differential Revisions:
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Comment (by simonpj):

 > This would be easier to explain, at least, and wouldn't require much
 upheaval either. Actually, this is probably simpler than my idea in
 comment:7.

 I don't think so.
 {{{
 type C a = X a Num
 type X a b = b a
 }}}
 I really don't want to put enough cleverness in the renamer to expand type
 synonyms on the fly.

 Let's see how keen our users are.

 Simon

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7543#comment:10>
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