Stab at immutable XML stuff

SO.scala

// see http://stackoverflow.com/questions/11130684/modify-xml-in-scala-without-mutation

import scala.xml._
import scala.xml.transform._

object BlankReplacer extends BasicTransformer {
  override def transform(n: Node): NodeSeq = n match {
    case <blank/> => {
      <input name={ "blank.%d" }/>
    }
    case elem: Elem => elem.copy(child=elem.child.flatMap(transform _))
    case _ => n
  }
}

val q = <text>The capitals of Bolivia are <blank/> and <blank/>.</text>

val qt = BlankReplacer(q).toString

lazy val n: Stream[Int] = Stream.cons(1, n.map(_ + 1))

// for any qt
qt.format(n.take(qt.toString.count(_ == '%')).toArray:_*)