[GHC] #15943: "ASSERT failed" with quantified constraints

[GHC]

#15943: "ASSERT failed" with quantified constraints
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        Reporter:  Iceland_jack      |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.6.3
       Component:  Compiler          |              Version:  8.6.2
      Resolution:                    |             Keywords:
                                     |  QuantifiedConstraints
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by Iceland_jack):

 It works if we replace `(->)` with the representationally equal `Fun`

 {{{#!hs
 newtype Fun a b = Fun (a -> b)

 instance Ríki Type where
   type Hom False = Fun
   type Hom True  = Op
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15943#comment:1>
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