--- a/progs/lexer/lexer.sc	Sat Nov 11 10:08:33 2023 +0000
+++ b/progs/lexer/lexer.sc	Fri Nov 17 20:06:43 2023 +0000
@@ -1,4 +1,4 @@
-// A simple lexer inspired by work of Sulzmann & Lu
+// A simple lexer inspired by work of Sulzmann $ Lu
 //==================================================
 //
 // Call the test cases with 
@@ -43,10 +43,9 @@
 implicit def string2rexp(s : String) : Rexp = 
   charlist2rexp(s.toList)
 
-// to use & for records, instead of $ which had
-// its precedence be changed in Scala 3
+
 extension (s: String) {
-  def & (r: Rexp) = RECD(s, r)
+  def $ (r: Rexp) = RECD(s, r)
 }
 
 extension (r: Rexp) {
@@ -60,7 +59,7 @@
   case ONE => true
   case CHAR(_) => false
   case ALT(r1, r2) => nullable(r1) || nullable(r2)
-  case SEQ(r1, r2) => nullable(r1) && nullable(r2)
+  case SEQ(r1, r2) => nullable(r1) $$ nullable(r2)
   case STAR(_) => true
   case RECD(_, r1) => nullable(r1)
 }
@@ -209,14 +208,14 @@
 val STRING: Rexp = "\"" ~ SYM.% ~ "\""
 
 
-val WHILE_REGS = (("k" & KEYWORD) | 
-                  ("i" & ID) | 
-                  ("o" & OP) | 
-                  ("n" & NUM) | 
-                  ("s" & SEMI) | 
-                  ("str" & STRING) |
-                  ("p" & (LPAREN | RPAREN)) | 
-                  ("w" & WHITESPACE)).%
+val WHILE_REGS = (("k" $ KEYWORD) | 
+                  ("i" $ ID) | 
+                  ("o" $ OP) | 
+                  ("n" $ NUM) | 
+                  ("s" $ SEMI) | 
+                  ("str" $ STRING) |
+                  ("p" $ (LPAREN | RPAREN)) | 
+                  ("w" $ WHITESPACE)).%
 
 
 // Two Simple While Tests