[GHC] #12425: With -O1 and above causes ghc to use all available memory before being killed by OOM killer

[GHC]

#12425: With -O1 and above causes ghc to use all available memory before being
killed by OOM killer
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        Reporter:  erikd             |                Owner:
            Type:  bug               |               Status:  new
        Priority:  high              |            Milestone:  8.0.2
       Component:  Compiler          |              Version:  8.0.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  Other             |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by erikd):

 @thomie Oh wow, that change you suggested (switching from `liftM` to
 `liftA`) prevents this problem in `conduit-find` even with stock 8.0.1.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12425#comment:4>
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