[GHC] #5927: A type-level "implies" constraint on Constraints

[GHC]

#5927: A type-level "implies" constraint on Constraints
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        Reporter:  illissius         |                Owner:
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler (Type    |              Version:  7.4.1
  checker)                           |
      Resolution:                    |             Keywords:
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):

 I believe `MonadTrans` should be

 {{{#!hs
 class forall m. Monad m `Implies` Monad (t m) => MonadTrans t where
   lift :: Monad m => m a -> (t m) a
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/5927#comment:22>
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