diff -r b7a6436c7758 -r 904de68a27a4 solutions/cw2/lexer.sc
--- a/solutions/cw2/lexer.sc	Thu Nov 10 23:49:29 2022 +0000
+++ b/solutions/cw2/lexer.sc	Tue Nov 15 11:34:33 2022 +0000
@@ -196,6 +196,11 @@
   }
 }
 
+def ders_simp(cs: List[Char], r: Rexp) : Rexp = cs match {
+  case Nil => r
+  case c::cs => ders_simp(cs, simp(der(c, r))._1)
+} 
+
 def lexing_simp(r: Rexp, s: String) = env(lex_simp(r, s.toList))
 
 // Language specific code
@@ -221,7 +226,7 @@
                   ("w" $ WHITESPACE) | 
                   ("i" $ ID) | 
                   ("n" $ NUM) |
-		  ("c" $ COMMENT)).%
+		              ("c" $ COMMENT)).%
 
 def esc(raw: String): String = {
   import scala.reflect.runtime.universe._
@@ -346,7 +351,10 @@
   case ALT(r1, r2) => 1 + size(r1) + size (r2)
   case SEQ(r1, r2) => 1 + size(r1) + size (r2)
   case STAR(r1) => 1 + size(r1)
+  case PLUS(r1) => 1 + size(r1)
   case NTIMES(r1, n) => 1 + size(r1)
+  case RECD(_, r1) => 1 + size(r1)
+  case RANGE(_) => 1
 }
 
 val reg = SEQ(STAR(STAR(CHAR('a'))), CHAR('b'))
@@ -355,3 +363,10 @@
 size(simp(der('a', reg))._1) // 8
 size(simp(der('a', der('a', reg)))._1) // 8
 
+
+
+// python tests
+println(size(WHILE_REGS))
+println(size(ders_simp("r".toList, WHILE_REGS)))
+println(size(ID))
+println(size(ders_simp("read".toList, ID)))