scalaDebugRepl.scala

/*
You'll see all kinds of different programatic scala REPL solutions out there, but for me they all have at least one of the following problems:
- Crash before prompt appears if you previously used repl.intp.bind before starting it.
- Prompt appears but every command crashes
- Works but no access to variables before the REPL started
- Works... but intermittently
....After a bunch of testing, I eventually reached the conclusion that the repl.intp isn't ready yet... so I start a Future
that'll bind the variable 2 seconds after the repl starts. So far this has been the reliable method.
*/
import scala.tools.nsc.interpreter.ILoop
import scala.tools.nsc.Settings
import scala.concurrent.Future
import scala.concurrent.ExecutionContext.Implicits.global

def prompt(myvar:Any) = {
  val repl = new ILoop
  val settings = new Settings
  settings.usejavacp.value = true
  repl.settings = settings
  repl.in = SimpleReader()
  repl.createInterpreter()
  repl.intp.initializeSynchronous()
  val gf = repl.getClass.getDeclaredField("globalFuture")
  gf.setAccessible(true)
  gf.set(repl, scala.concurrent.Future.successful(true)) //This person says to do this - http://stackoverflow.com/a/28062917
  Future {
    Thread.sleep(2000)           
    repl.intp.bind("myvar", "Any", myvar)                 
  }
  repl.process(settings)  
  repl.closeInterpreter()  
}