[GHC] #13876: Check 'pure' method of 'Applicative (WrappedMonad m)'

[GHC]

#13876: Check 'pure' method of 'Applicative (WrappedMonad m)'
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           Reporter:  Iceland_jack   |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.0.1
           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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 Should

 {{{#!hs
 instance Monad m => Applicative (WrappedMonad m) where
   pure = WrapMonad . pure

   WrapMonad f <*> WrapMonad v = WrapMonad (f `ap` v)
 }}}

 not use `return`?


 {{{#!hs
 instance Monad m => Applicative (WrappedMonad m) where
   pure = WrapMonad . return

   WrapMonad f <*> WrapMonad v = WrapMonad (f `ap` v)
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13876>
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