[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):

 That example is one where the result type depends on the parameters… but
 don’t see why we need that restriction – this code shows that it would be
 beneficial and not crash to allow it. The note `[The polymorphism rule of
 join points]` basically says “We need this restriction because the CPS
 translation would not be easily typable, but that is not very convincing.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14610#comment:15>
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