scala.tools.nsc.IMain within Play 2.1 - scala

Question

I googled a lot and am totally stuck now. I know, that there are similar questions but please read to the end. I have tried all proposed solutions and none did work.
I am trying to use the IMain class from scala.tools.nsc within a Play 2.1 project (Using Scala 2.10.0).
Controller Code
This is the code, where I try to use the IMain in a Websocket. This is only for testing.
object Scala extends Controller {
def session = WebSocket.using[String] { request =>
val interpreter = new IMain()
val (out,channel) = Concurrent.broadcast[String]
val in = Iteratee.foreach[String]{ code =>
interpreter.interpret(code) match {
case Results.Error => channel.push("error")
case Results.Incomplete => channel.push("incomplete")
case Results.Success => channel.push("success")
}
}
(in,out)
}
}
As soon as something gets sent over the Websocket the following error gets logged by play:
Failed to initialize compiler: object scala.runtime in compiler mirror not found.
** Note that as of 2.8 scala does not assume use of the java classpath.
** For the old behavior pass -usejavacp to scala, or if using a Settings
** object programatically, settings.usejavacp.value = true.
Build.scala
object ApplicationBuild extends Build {
val appName = "escalator"
val appVersion = "1.0-SNAPSHOT"
val appDependencies = Seq(
"org.scala-lang" % "scala-compiler" % "2.10.0"
)
val main = play.Project(appName, appVersion, appDependencies).settings(
)
}
What I have tried so far
All this didn't work:
I have included fork := true in the Build.scala
A Settings object with:
embeddedDefaults[MyType]
usejavacp.value = true
The soultion proposed as answer to Question Embedded Scala REPL inherits parent classpath
I dont know what to do now.

Answer 1

The problem here is that sbt doesnt add scala-library to the class path.
The following workaround works.
First create a folder lib in the top project directory(the parent of app,conf etc) and copy there the scala-library.jar
Then you can use the following code to host an interpreter :
val settings = new Settings
settings.bootclasspath.value +=scala.tools.util.PathResolver.Environment.javaBootClassPath + File.pathSeparator + "lib/scala-library.jar"
val in = new IMain(settings){
override protected def parentClassLoader = settings.getClass.getClassLoader()
}
val res = in.interpret("val x = 1")
The above creates the bootclasspath by adding to the java class the scala library. It's not a problem with play framework it comes from the sbt. The same problem occures for any scala project when it runs with sbt. Tested with a simple project. When it runs from eclipse its works fine.
EDIT: Link to sample project demonstrating the above.`

Answer 2

I wonder if the reflect jar is missing. Try adding this too in appDependencies.
"org.scala-lang" % "scala-reflect" % "2.10.0"