Missing non-visible code

Author: TobiasWrigstad

xml/chapter5/section4/subsection4.xml

@@ -505,6 +505,8 @@ const eceval_controller =
 
 "ev_sequence_start",
  assign("unev", list(op("sequence_statements"), reg("comp"))),
+ test(list(op("is_empty_sequence"), reg("unev"))),
+ branch(label("ev_empty_sequence")),
  save("continue"),
 
 "ev_sequence",
@@ -526,6 +528,10 @@ const eceval_controller =
  restore("continue"),
  go_to(label("eval_dispatch")),
 
+"ev_sequence_empty",
+ assign("val", constant(undefined)),
+ go_to(reg("continue")), 
+
  "ev_conditional",
  save("comp"), // save expression for later
  save("env"),
@@ -675,6 +681,7 @@ const eceval_operations =
  list("first_statement" , first_statement),
  list("rest_statements" , rest_statements),
  list("is_last_statement" , is_last_statement),
+ list("is_empty_sequence" , is_empty_sequence),
  list("sequence_statements" , sequence_statements),
 
  // eval functions from meta-circular evaluator