diff -r c235e0aeb8df -r 539b2e88f5b9 progs/app6.scala
--- a/progs/app6.scala	Fri Oct 02 08:48:46 2015 +0100
+++ b/progs/app6.scala	Fri Oct 02 23:44:14 2015 +0100
@@ -1,22 +1,18 @@
 def simp(r: Rexp): Rexp = r match {
   case ALT(r1, r2) => {
-    val r1s = simp(r1)
-    val r2s = simp(r2)
-    (r1s, r2s) match {
-      case (NULL, _) => r2s
-      case (_, NULL) => r1s
-      case _ => if (r1s == r2s) r1s else ALT(r1s, r2s)
+    (simp(r1), simp(r2)) match {
+      case (NULL, r2s) => r2s
+      case (r1s, NULL) => r1s
+      case (r1s, r2s) => if (r1s == r2s) r1s else ALT(r1s, r2s)
     }
   }
   case SEQ(r1, r2) => {
-    val r1s = simp(r1)
-    val r2s = simp(r2)
-    (r1s, r2s) match {
+    (simp(r1), simp(r2)) match {
       case (NULL, _) => NULL
       case (_, NULL) => NULL
-      case (EMPTY, _) => r2s
-      case (_, EMPTY) => r1s
-      case _ => SEQ(r1s, r2s)
+      case (EMPTY, r2s) => r2s
+      case (r1s, EMPTY) => r1s
+      case (r1s, r2s) => SEQ(r1s, r2s)
     }
   }
   case NTIMES(r, n) => NTIMES(simp(r), n)