25

Question says it all.

(Yet, the details of how to get access to the shift and reset operations has changed over the years. Old blog entries and Stack Overflow answers may have out of date information.)

See also What are Scala continuations and why use them? which talks about what you might want to do with shift and reset once you have them.

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Seth Tisue
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2 Answers2

29

Scala 2.11

The easiest way is to use sbt:

scalaVersion := "2.11.6"

autoCompilerPlugins := true

addCompilerPlugin(
  "org.scala-lang.plugins" % "scala-continuations-plugin_2.11.6" % "1.0.2")

libraryDependencies +=
  "org.scala-lang.plugins" %% "scala-continuations-library" % "1.0.2"

scalacOptions += "-P:continuations:enable"

In your code (or the REPL), do import scala.util.continuations._

You can now use shift and reset to your heart's content.

historical information for Scala 2.8, 2.9, 2.10

You have to start scala (or scalac) with the -P:continuations:enable flag.

In your code, do import scala.util.continuations._

You can now use shift and reset to your heart's content.

If you're using sbt 0.7, see https://groups.google.com/forum/#!topic/simple-build-tool/Uj-7zl9n3f4

If you're using sbt 0.11+, see https://gist.github.com/1302944

If you're using maven, see http://scala-programming-language.1934581.n4.nabble.com/scala-using-continuations-plugin-with-2-8-0-RC1-and-maven-td2065949.html#a2065949

Seth Tisue
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    Note that if you are using the eclipse plugin, put "continuations:enable" in the "P" compiler preferences, and also be sure to clear out the "Xpluginsdir" pref, as the default values in there seem to interfere with using the continuations plugin. – Mitch Blevins Apr 21 '10 at 15:52
  • for Eclipse users, see http://stackoverflow.com/questions/4556540/continuations-in-scala-2-8-1-and-eclipse – Seth Tisue Jan 04 '11 at 17:34
  • Thank you Mitch Blevins -- I was having trouble until I cleared out the Xpluginsdir pref. Could not find that advice anywhere else. – Eric Jun 04 '11 at 02:36
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    Thanks Mitch, I also had to clear the Xpluginsdir field. Furthermore it didn't work until I did a clean. – Ben Challenor Jun 16 '11 at 21:17
  • Anyone please tell me how to use with gradle? – Quy Tang Oct 01 '16 at 16:20
7

Non SBT solution:

scala -Xpluginsdir /.../scala/lib/ -P:continuations:enable

Works on scala 2.11.6, but the plugin/library said that it will no longer be included with Scala 2.12

krrr
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    Note that perhaps someone will update the plugin to work with 2.12, even though it will definitely no longer be bundled. – Seth Tisue Sep 19 '15 at 00:30