The class WordExp provides regular word expressions. Users have to instantiate type member _regexpT <: RegExp (from class Base) and a type member _labelT <: Label. Here is a short example:

  import scala.util.regexp._
  import scala.util.automata._
  object MyLang extends WordExp {
    type _regexpT = RegExp
    type _labelT = MyChar

    case class MyChar(c:Char) extends Label
  }
  import MyLang._
  // (a* | b)*
  val rex = Star(Alt(Star(Letter(MyChar('a'))),Letter(MyChar('b'))))
  object MyBerriSethi extends WordBerrySethi {
    override val lang = MyLang
  }
  val nfa = MyBerriSethi.automatonFrom(Sequ(rex), 1)