diff -r 3b9496db3fb9 -r 3390e863d796 progs/re4.scala
--- a/progs/re4.scala	Tue Sep 26 14:07:29 2017 +0100
+++ b/progs/re4.scala	Tue Sep 26 14:08:49 2017 +0100
@@ -1,4 +1,6 @@
-    
+// Version which attempts to move whole strings, not
+// just characters, under derivatives whenever possible
+   
 abstract class Rexp
 case object ZERO extends Rexp
 case object ONE extends Rexp
@@ -50,6 +52,7 @@
   case r => r
 }
 
+// *new*
 // derivative w.r.t. a string (iterates der)
 def ders2(s: List[Char], r: Rexp) : Rexp = (s, r) match {
   case (Nil, r) => r
@@ -68,6 +71,9 @@
 //one or zero
 def OPT(r: Rexp) = ALT(r, ONE)
 
+
+// Test Cases
+
 def EVIL1(n: Int) = SEQ(NTIMES(OPT(CHAR('a')), n), NTIMES(CHAR('a'), n))
 val EVIL2 = SEQ(STAR(STAR(CHAR('a'))), CHAR('b'))
 
@@ -79,7 +85,6 @@
   (end - start)/(i * 1.0e9)
 }
 
-// warmup
 //test: (a?{n}) (a{n})
 for (i <- 1 to 7000001 by 500000) {
   println(i + " " + "%.5f".format(time_needed(2, matcher(EVIL1(i), "a" * i))))