[GHC] #11450: Associated types at wrong type in instance

18 Jan 2016

      #11450: Associated types at wrong type in instance
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           Reporter:  simonpj        |             Owner:
               Type:  bug            |            Status:  new
           Priority:  high           |         Milestone:  8.0.1
          Component:  Compiler       |           Version:  7.10.3
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 Consider
 {{{
 class C x where
   type T x

 instance C (Either a b) where
   type T (Either b a) = b -> a
 }}}
 This is bogus, because the equation for `T` has the parameters to `Either`
 reversed.

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Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11450
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