(define (get-prefix name)
  (string-join (drop-right (string-split name ".") 1) "."))

...

(define (ns-record row)
  (let* ((do-name (string-downcase (alist-ref 'do_name row)))
		 (do-prefix (get-prefix do-name))
		 (quoted-do-name (irregex-quote do-name))
		 (ho-name (string-downcase (alist-ref 'ho_name row)))
		 (ho-name (irregex-replace "\\.+$" ho-name ""))
		 (ho-prefix (if (equal? ho-name "") "" (get-prefix ho-name)))
		 (ho-ipv4 (string-downcase (alist-ref 'ho_ipv4 row)))
		 (ho-ipv6 (string-downcase (alist-ref 'ho_ipv6 row)))
		 (hd-id (alist-ref 'hd_id row))
		 (do-ttl (alist-ref 'do_ttl row)))

...

Error: (string-split) bad argument type - not a string: #f

	Call history:

	genzone.la.scm:57: alist-ref	  
	genzone.la.scm:57: string-downcase	  
	genzone.la.scm:58: get-prefix	  
	genzone.la.scm:26: display	  
	genzone.la.scm:27: newline	  
	genzone.la.scm:28: string-split	  
	genzone.la.scm:28: drop-right	  
	genzone.la.scm:28: string-join	  
	genzone.la.scm:59: irregex-quote	  
	genzone.la.scm:60: alist-ref	  
	genzone.la.scm:60: string-downcase	  
	genzone.la.scm:61: irregex-replace	  
	genzone.la.scm:62: get-prefix	  
	genzone.la.scm:26: display	  
	genzone.la.scm:27: newline	  
	genzone.la.scm:28: string-split