scala.reflect.internal.FatalError: package scala does not have a member Int

Question

I am currently working on a project using Scala and Play Framework 2. I want to compile some Scala code during runtime and get the result from the interpreter. I found some examples on the internet and finally came up with the following code:

package controllers

import play.api.mvc.{Action, Controller}
import javax.script.ScriptEngineManager

class Interpreter extends Controller {

    val interpreter = new ScriptEngineManager().getEngineByName("scala")
    val settings = interpreter.asInstanceOf[scala.tools.nsc.interpreter.IMain].settings
    settings.embeddedDefaults[Interpreter]
    settings.usejavacp.value = true

    def index = Action {
        Ok(views.html.interpreter())
    }

    def interpret(input: String) = Action { 
        implicit request => interpreter.eval("1 to 10 foreach println")
        Ok("Got: " + input)
    }
}

object Interpreter

My problem is that I always get an error from scala.reflect.internal.FatalError: "package scala does not have a member Int", when trying to run this code. After some research I found similar problems described in this posts:

Scala and Play 2.0 Plugins Update 0.38.437 is Out

Scala compiler error: package api does not have a member materializeWeakTypeTag

My current Scala version is 2.11.4, so I tried to switch to a different "scala-compiler" and "scala-library" versions in my "build.sbt" file, but with no success. Like it was mentioned in the posts above it is probably a bug in Scala. I wondered if somebody has a solution or perhaps any workaround for the described problem.

Thanks in advance for any help or advice.

Answer 1

The issue is in classpath in projects using Scala and Play Framework 2. It can be resolved by populating classpath from SBT to the application:

Add to build.sbt file:

val sbtcp = taskKey[Unit]("sbt-classpath")

sbtcp := {
  val files: Seq[File] = (fullClasspath in Compile).value.files
  val sbtClasspath : String = files.map(x => x.getAbsolutePath).mkString(":")
  println("Set SBT classpath to 'sbt-classpath' environment variable")
  System.setProperty("sbt-classpath", sbtClasspath)
}

compile  <<= (compile in Compile).dependsOn(sbtcp)

Code:

package controllers

import play.api.mvc.{Action, Controller}
import javax.script.ScriptEngineManager

class Interpreter extends Controller {

    val interpreter = new ScriptEngineManager().getEngineByName("scala")
    val settings = interpreter.asInstanceOf[scala.tools.nsc.interpreter.IMain].settings
    //settings.embeddedDefaults[Interpreter] // not need
    //settings.usejavacp.value = true // not need
    val sbtClasspath = System.getProperty("sbt-classpath")
    settings.classpath.value = s".:${sbtClasspath}" // <-- this line fix the problem

    def index = Action {
        Ok(views.html.interpreter())
    }

    def interpret(input: String) = Action { 
        implicit request => interpreter.eval("1 to 10 foreach println")
        Ok("Got: " + input)
    }
}

object Interpreter

In production should be used another scenario to get a correct classpath.

Probably using a '-cp' or '-classpath' key from the command line.