1 // Version with simplification during derivatives;

     1 // Version with simplification during derivatives;

     2 // this keeps the regular expressions small, which

     2 // this keeps the regular expressions small, which

     3 // is good for run-time

     3 // is good for run-time

     4 

     5 

     5 abstract class Rexp

     6 abstract class Rexp

     6 case object ZERO extends Rexp

     7 case object ZERO extends Rexp

     7 case object ONE extends Rexp

     8 case object ONE extends Rexp

     8 case class CHAR(c: Char) extends Rexp

     9 case class CHAR(c: Char) extends Rexp