awk.egg question

I am trying to determine whether or not the awk.egg is working properly on my 
system.

Solaris/x86, Chicken 2.207

Running

cat /etc/passwd | csi -R awk -s awk-egg-test.scm

Gets me a page and a half of traceback, starting with:

Error: unbound variable: string-split-fields

The file I am using, contains the "sort password" example from the awk.egg web 
page:

(require-extension awk)

(define (read-passwd . port)
  (let ([line (apply read-line port)])
    (if (eof-object? line)
        (values line #f)
        (values line (string-split-fields ":" line #:infix)) ) ) )

(for-each
 (lambda (entry) (print (cdr entry)))
 (sort
  (awk (read-passwd) (line fields) ([ans '()])
    (#t (cons (cons (car fields) line) ans)) )
  (lambda (x y) (string<? (car x) (car y))) ) )

(removing the require-extension line does not change the script's behavior)

Suggestions, comments, code to try out welcome.

Also, I suggest that tests be packaged along with the eggs (where appropriate) 
that can be used to show that the egg is working as expected.

Cordially

Patrick Giagnocavo
patrick@xxxxxxxx