[GHC] #11070: Type-level arithmetic of sized-types has weaker inference power than in 7.8

[GHC]

#11070: Type-level arithmetic of sized-types has weaker inference power than in 7.8
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        Reporter:  cactus            |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  7.10.2
      Resolution:                    |             Keywords:  TypeFamilies
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  GHC rejects       |  Unknown/Multiple
  valid program                      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by RyanGlScott):

 Amusingly enough, this now typechecks again on GHC 8.0 and later. Is this
 a good thing?

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11070#comment:5>
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