Emulating Groovy's Builder in Scala

html-builder-mutable-state.scala

class HtmlBuilder {
  var html: NodeSeq = NodeSeq.Empty
  def b(f: (HtmlBuilder) => Unit): Unit = appendNodes(<b>{val b1 = new HtmlBuilder; f(b1); b1.html}</b>)
  def a(href: String)(f: (HtmlBuilder) => Unit): Unit = appendNodes(<a href={href}>{val b1 = new HtmlBuilder; f(b1); b1.html}</a>)
  def text(text: String): Unit = appendNodes(Text(text))
  def appendNodes(nodes: xml.Node*) = html = html ++ nodes
}

implicit val builder: HtmlBuilder = new HtmlBuilder
import builder._
a(href = "http://scala-lang.org") { builder => import builder._
  b { builder => import builder._
    text("Scala Lang Website")
  }
}
assert(builder.html.toString == """<a href="http://scala-lang.org"><b>Scala Lang Website</b></a>""")