class Miner(args: Args) extends Job(args) {

  def fetchUrl(url:String) = {
    ...
  }

  TextLine(args("input")).map(url: String => fetchUrl(url))
    .write(args("output"))
}

TextLine(args("input")).map(fetchUrl)
    .write(args("output"))

val savings =
  items.mapTo(('price, 'discountedPrice) -> 'savings) {
    x : (Float, Float) =>
    val (price, discountedPrice) = x
    price - discountedPrice
  }