Print stdin without duplicates

gistfile1.scala

object Unique {
  def main(args: Array[String]) {

    val h = collection.mutable.Set[String]()
    def uniq(ln : String) = Some(ln) filter (h.add(_))
    
    for (ln <- io.Source.stdin.getLines;
         ln <- uniq(ln)) {
      println(ln)
    }
  }
}