[GHC] #13309: Use liftA2 in ApplicativeDo

[GHC]

#13309: Use liftA2 in ApplicativeDo
-------------------------------------+-------------------------------------
           Reporter:  dfeuer         |             Owner:  (none)
               Type:  task           |            Status:  new
           Priority:  normal         |         Milestone:  8.4.1
          Component:  Compiler       |           Version:  8.1
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  Runtime
  Unknown/Multiple                   |  performance bug
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
-------------------------------------+-------------------------------------
 Now that `liftA2` is in `Applicative`, we want to be sure to use it when
 desugaring `ApplicativeDo`.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13309>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler