[GHC] #14610: newtype wrapping of a monadic stack kills performance

[GHC]

#14610: newtype wrapping of a monadic stack kills performance
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        Reporter:  mrkkrp            |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.6.1
       Component:  Compiler          |              Version:  8.2.2
      Resolution:                    |             Keywords:  JoinPoints
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Runtime           |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #14620            |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by nomeata):

 Ok, thanks for the clarification. Finally I get why that restriction is
 there. I will try to improve the Note about it (and pass it by you for
 confirmation).

 I think the transformation is possible, but it is somewhat non-local, as
 you need to move all casts inwards towards the recursive call, and then
 into the newly added parameter. Ff we find that there are performance
 gains to be won, then it might be worth it!

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14610#comment:21>
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