jade or DSSSL: either one is strange - compared to Scheme

[Joerg Wittenberger <Joerg.Wittenberger@xxxxxxxxx>]

Hello,

This is a snippet of a DSSSL Style sheet. It should customize Norman
Walsh's famous docbook style sheets.

The original style sheets labels nested sections to arbitrary
depth. I'd like to restrict those labels to a level up to three.

Implementation idea

I assumed that I could overwrite the definition of section-autolabel
(within my derived style sheet) as follows:

(define section-autolabel
  (let ((old-definition section-autolabel))
    (lambda (nd #!optional (force-label? #f))
      (let ((depth (node-list-length (ancestor (normalize "section") nd))))
        (if (> depth 3)
            ""
            (old-definition nd force-label?))))))

Problem

Unfortunatly jade complains 

...:E: loop in specification of value of "section-autolabel"

Any ideas what's wrong? Is this what the DSSSL spec requires? 


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