diff -r f71399fe3fdc -r 36799f7b9702 progs/lexer/lexer.sc
--- a/progs/lexer/lexer.sc	Fri Oct 31 11:25:14 2025 +0000
+++ b/progs/lexer/lexer.sc	Fri Oct 31 19:26:11 2025 +0000
@@ -43,9 +43,7 @@
 
 given Conversion[String, Rexp] = (s => charlist2rexp(s.toList))
 
-//extension (s: String) {
-//  def $ (r: Rexp) = RECD(s, r)
-//}
+
 extension (s: String) {
   def $ (r: Rexp) = RECD(s, r)
   def | (r: Rexp) = ALT(s, r)
@@ -81,7 +79,7 @@
     if (nullable(r1)) ALT(SEQ(der(c, r1), r2), der(c, r2))
     else SEQ(der(c, r1), r2)
   case STAR(r) => SEQ(der(c, r), STAR(r))
-  case RECD(_, r1) => der(c, r1)
+  case RECD(label, r1) => der(c, r1)
 }
 
 // extracts a string from a value