--- a/progs/matcher/re3.sc	Mon Sep 25 13:14:34 2023 +0100
+++ b/progs/matcher/re3.sc	Mon Sep 25 15:12:11 2023 +0100
@@ -1,10 +1,10 @@
-// A version of the matcher with simplification 
+// A version of the simple matcher with simplification 
 // of derivatives
 //
-// this keeps the regular expressions small, which
+// this keeps the regular expressions (often) small, which
 // is good for the run-time
 // 
-// call the test cases with X = {1,2}
+// call the test cases with X = {1,2,3,4}
 //
 //   amm re3.sc testX
 //
@@ -23,7 +23,6 @@
 case class NTIMES(r: Rexp, n: Int) extends Rexp 
 
 
-
 // the nullable function: tests whether the regular 
 // expression can recognise the empty string
 def nullable (r: Rexp) : Boolean = r match {
@@ -67,7 +66,7 @@
   case r => r
 }
 
-// the derivative w.r.t. a string (iterates der)
+// the derivative w.r.t. a string (iterates der and simp)
 def ders(s: List[Char], r: Rexp) : Rexp = s match {
   case Nil => r
   case c::s => ders(s, simp(der(c, r)))
@@ -81,7 +80,7 @@
 // Test Cases
 //============
 
-// one or zero
+// optional is still just defined
 def OPT(r: Rexp) = ALT(r, ONE)
 
 // evil regular expressions: (a?){n} a{n}  and (a*)* b
@@ -130,7 +129,8 @@
 
 
 // now the size of the derivatives grows 
-// much, much slower
+// much, much slower and actually maxes out
+// at size 8
 
 size(ders("".toList, EVIL2))      // 5
 size(ders("a".toList, EVIL2))     // 8
@@ -139,6 +139,8 @@
 size(ders("aaaa".toList, EVIL2))  // 8
 size(ders("aaaaa".toList, EVIL2)) // 8
 
+size(ders(("a" * 20000).toList, EVIL2)) // 8
+
 
 @arg(doc = "All tests.")
 @main