object ListBuilding {
	object Builder {
	  def create[a]: Builder[a] = new ListBuilder[a]()
	}
	
  trait Builder[a] extends Function1[a, Builder[a]] {
    def get: List[a]
		def `!`: List[a] = get
		def `$`(x: =>a): Builder[a]
		def success: Boolean
	}
  
  class EndBuilding[a] extends Builder[a] {
  	def apply(x: a) = this
  	override def get = List()
  	def `$`(x: =>a): Builder[a] = this
  	override def success = false
  }
  
	class ListBuilder[a](init : List[a]) extends Builder[a] {
	  override def success = true
		def apply(x: a): Builder[a] = new ListBuilder(x :: init)
		override def `$`(x: =>a): Builder[a] = {
		  lazy val copy = x;
		  
			try {
			  apply(x)
			} catch {
	      case Again => `$`(copy)
				case End => new EndBuilding[a]
			}			
		}
		
		override def get = init reverse
		
		def this(init: a) = this(List(init))
		def this() = this(List())
	}
	
	object End extends Throwable
	object Again extends Throwable
}

object BuildingListTest {
	import ListBuilding._
	
	def main(args : Array[String]) {

	  def ask(message: String, predicate: String => Boolean) = {
	  	println (message)
	    val value = readLine
	    if(value == "quit") throw End
	    else if(predicate(value)) throw Again
	    else value 
	  }
	  
	  val result = 
			Builder.create[String]	$
			ask ("Favourite number? (must be 42)", "42" !=) $ 
			ask ("The favorite president? (cannot be bush)",  "Bush" ==) $
			ask ("Is Java important? (not empty)", "" ==) ;

	  if(result success) {
		  println (result !)
		} else {
		  println ("quitted")
		}
	}
}

BuildingListTest.main(Array())