[GHC] #10833: Use injective type families (decomposition) when dealing with givens

[GHC]

#10833: Use injective type families (decomposition) when dealing with givens
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        Reporter:  jstolarek         |                Owner:  (none)
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler (Type    |              Version:  7.10.2
  checker)                           |             Keywords:  TypeFamilies,
      Resolution:                    |  InjectiveFamilies
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #6018, #11511,    |  Differential Rev(s):
  #12199                             |
       Wiki Page:                    |
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Comment (by nfrisby):

 This scenario seems like an excellent use-case for a typechecker plugin:
 so that power users could opt-in to the soundness conjecture. Do we have
 an estimate of if that's possible give current TC plugin API and how
 complicated it would be to implement? Thanks.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10833#comment:10>
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