Tentative JSON pretty printer in Scala

Sca2Main.scala

import scala.io._
import scala.util.parsing.json._

object Sca2Main {
  def main(args: Array[String]){
		val url = "http://search.twitter.com/search.json?q=umitanuki"
		val parsed = JSON.parseRaw(Source.fromURL(url).getLines.mkString)
		parsed match{
			case Some(x:JSONObject) => println("object")
			case Some(y:JSONArray) => println("array")
			case Some(z:JSONType) => println("jsontype")
			case None => println("none")
			case _ => 
		}
		print(pprint(parsed, 0))
	}
	def pprint(j: Option[Any], l:Int):String = {
		val indent = (for(i <- List.range(0, l)) yield "  ").mkString
		j match{
			case Some(o:JSONObject) => {
				List("{",
				o.obj.keys.map(key => indent + "  " + "\"" + key + "\":" + pprint(o.obj.get(key), l + 1)).mkString(",\n"),
				indent + "}").mkString("\n")
			}
			case Some(a:JSONArray) => {
				List("[",
				a.list.map(v => indent + "  " + pprint(Some(v), l + 1)).mkString(",\n"),
				indent + "]").mkString("\n")
			}
			case Some(s: String) => "\"" + s + "\""
			case Some(n: Number) => n.toString
			case None => "null"
			case _ => "undefined"
		}
	}
}