--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/progs/app03.scala	Sat Oct 18 02:08:17 2014 +0100
@@ -0,0 +1,8 @@
+abstract class Rexp
+case object NULL extends Rexp
+case object EMPTY extends Rexp
+case class CHAR(c: Char) extends Rexp
+case class ALT(r1: Rexp, r2: Rexp) extends Rexp 
+case class SEQ(r1: Rexp, r2: Rexp) extends Rexp 
+case class STAR(r: Rexp) extends Rexp 
+case class REC(x: String, r: Rexp) extends Rexp