Interpreter.scala

import tools.nsc.interpreter.Results._
import tools.nsc.interpreter.IMain
import tools.nsc.Settings

class ResultHolder(var value : Any)

class ScalaInterpreter(settings: Settings) extends IMain(settings) {

    val writer = new java.io.StringWriter()

    def resetWriter = {
        writer.getBuffer.setLength(0)
    }
}

object Interpreter {

    val settings = new Settings
    settings.usejavacp.value = true

    val interpreter = new ScalaInterpreter(settings);

    def bind(name : String, value : AnyRef) {
        interpreter.bind(name, value.getClass.getName, value)
    }

    def eval(code : String) : Any = {

        interpreter.resetWriter

        val holder = new ResultHolder(null)
        bind("$result__", holder);

        val result = interpreter.interpret("$result__.value = " + code);

        result match {
            case Success => holder.value
            case Error => throw new RuntimeException("error in: '" + code + "'\n" + interpreter.writer toString)
            case Incomplete => throw new RuntimeException("incomplete in :'" + code + "'\n" + interpreter.writer toString)
        }
    }
}