--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Attic/rev.scala	Thu Jul 30 13:50:54 2020 +0100
@@ -0,0 +1,8 @@
+def rev(r: Rexp) : Rexp = r match {
+  case ZERO => ZERO
+  case ONE => ONE
+  case CHAR(c) => CHAR(c)
+  case ALT(r1, r2) => ALT(rev(r1), rev(r2))
+  case SEQ(r1, r2) => SEQ(rev(r2), rev(r1))
+  case STAR(r) => STAR(rev(r))
+}