--- a/progs/lexer/lexer.sc	Thu May 13 13:10:38 2021 +0100
+++ b/progs/lexer/lexer.sc	Mon Aug 30 14:18:08 2021 +0100
@@ -143,9 +143,7 @@
   (v:Val) => Sequ(f1(Empty), f2(v))
 def F_SEQ_Empty2(f1: Val => Val, f2: Val => Val) = 
   (v:Val) => Sequ(f1(v), f2(Empty))
-def F_RECD(f: Val => Val) = (v:Val) => v match {
-  case Rec(x, v) => Rec(x, f(v))
-}
+
 def F_ERROR(v: Val): Val = throw new Exception("error")
 
 // simplification