--- a/progs/re1.scala	Mon Oct 17 13:18:34 2016 +0100
+++ b/progs/re1.scala	Tue Oct 18 10:43:26 2016 +0100
@@ -5,6 +5,12 @@
 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 RANGE(cs: List[Char]) extends Rexp
+case class PLUS(r: Rexp) extends Rexp
+case class OPT(r: Rexp) extends Rexp
+case class NTIMES(r: Rexp, n : Int) extends Rexp
+case class NMTIMES(r: Rexp, n : Int, m : Int) extends Rexp
+
 
 // nullable function: tests whether the regular 
 // expression can recognise the empty string
@@ -15,6 +21,7 @@
   case ALT(r1, r2) => nullable(r1) || nullable(r2)
   case SEQ(r1, r2) => nullable(r1) && nullable(r2)
   case STAR(_) => true
+
 }
 
 // derivative of a regular expression w.r.t. a character