CODEWITHSUNDEEP
scalasbtread-eval-print-loopcontinuationsscala-2.10
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Reputation: 67280

Scala 2.10 and Continuations (akka-dataflow) in the sbt console

What is the status of the continuations plugin in Scala 2.10; I'm slightly confused. The following setup is in the Akka 2.2-SNAPSHOT documentation:

autoCompilerPlugins := true,
libraryDependencies <+= scalaVersion {
  v => compilerPlugin("org.scala-lang.plugins" % "continuations" % "2.10.0")
},
scalacOptions += "-P:continuations:enable",

First, the scalacOption doesn't work with 2.10 anymore, and the scalaVersion is not actually used in the library dependencies. If I naively go ahead with 2.10 and no special configurations (remove all of the above), and Akka 2.1.0:

import concurrent.ExecutionContext.Implicits.global
import akka.dataflow._

flow { "Hello world!" } onComplete println

I get an error indicating that the continuations plug-in is not enabled.

What what is the correct approach to enable continuations in Scala 2.10?

In particular: How can I drop into the sbt console and try out the above example with flow. It seems I also need to make sure the compiler plugin is enabled for the REPL?

EDIT: The scalacOptions entry does work, it seems I had a typo.

Upvotes: 2

Views: 570

Answers (1)

Mark Harrah
Mark Harrah

Reputation: 7019

With this build.sbt:

autoCompilerPlugins := true

scalaVersion := "2.10.0"

libraryDependencies +=
  compilerPlugin("org.scala-lang.plugins" % "continuations" % "2.10.0")

scalacOptions += "-P:continuations:enable"

the following continuations-only (no Akka) example works in the REPL:

scala> import scala.util.continuations._

scala> reset { val i = shift { body: (Int => Unit) => body(5);
     | println("done") }; println(i) }

Upvotes: 4

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