Embed Scala REPL

InterpreterTest.scala

object InterpreterTest {
  import scala.tools.nsc._
  import interpreter._

  def break(params: NamedParam*): Unit = {
    val repl = new ILoop
    repl.settings = new Settings
    repl.settings.Yreplsync.value = true
    repl.in = SimpleReader()
    repl.createInterpreter
    repl.intp.beQuietDuring {
      params.map(repl.intp.bind)
    }
    repl.loop
    repl.closeInterpreter
  }

  def breakIf(cond: => Boolean, params: NamedParam*): Unit =
    if (cond) break(params: _*)

  def main(args: Array[String]) {
    0 to 10 foreach { i =>
      breakIf(i == 5, NamedParam("j", i))
      println(i)
    }
  }
}

/*
 * Output:
$ scala -cp bin InterpreterTest
0
1
2
3
4

scala> j
res0: Int = 5

scala> :q
5
6
7
8
9
10

*/