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

[GHC]

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

 * owner:  jstolarek =>


Comment:

 In the "Injective Type Families for Haskell" we did not present a full
 proof of soundness of injective type families.  It might be the case that
 the proof requires solving
 [[http://www.win.tue.nl/rtaloop/problems/79.html|RTA #79]].  But we don't
 know for sure.  Richard argues that for this reason we should not make
 these changes to Core - if our conjecture that our proof holds turns out
 to be incorrect Core will become inconsistent.  So for the time being I am
 abandoning further work on this.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10833#comment:1>
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