[GHC] #11715: Constraint vs *

[GHC]

#11715: Constraint vs *
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        Reporter:  bgamari           |                Owner:
            Type:  bug               |               Status:  new
        Priority:  high              |            Milestone:  8.2.1
       Component:  Compiler (Type    |              Version:  8.0.1-rc1
  checker)                           |
      Resolution:                    |             Keywords:  Typeable
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 goldfire):

 What about this:

 {{{
 type family F a where
   F Int = Int
   F a   = Char

 foo :: F a -> a -> (a => r) -> r
 foo x y k = with x $ with y $ k
 }}}

 When `a` is specialized to `Int`, the body of `foo` is ambiguous, even
 though it isn't under other conditions. How do we resolve this?

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11715#comment:20>
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