[GHC] #13282: Introduce fast path through simplifier for static bindings

[GHC]

#13282: Introduce fast path through simplifier for static bindings
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        Reporter:  bgamari           |                Owner:  bgamari
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by bgamari):

 > Minor amendments:
 > * I think you only intend to allow saturated data constructor
 applications; though I'm not sure.
 > * Literals should also be considered static.

 Yes, I should have been more precise. I believe the right check is
 `exprIsConLike_maybe` and verifying that all of the value arguments are
 themselves binders or literals.

 > What about type applications of polymorphic data constructors to type
 variables? E.g.

 That is an interesting point; I think there is a reasonable argument to be
 made for considering type lambdas as static as well. This isn't what the
 patch (which has been a bit trickier than I thought due to unfoldings
 getting zapped in various unexpected places) currently implements though.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13282#comment:3>
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