Example of creating a `repeat { ... } until (...)` like control structure.

repeat-until.scala

import scala.annotation.tailrec

object controls {

    def repeat(body: => Unit) = new {
        @tailrec
        def until(condition: => Boolean) {
            body
            if (condition) () else until(condition)
        }
    }

    var i = 0;

    repeat {
        println("i = " + i)
        i = i + 1
    } until (i > 3)
}