;; eliminate-whitespace : (listof Symbol) (Bool -> Bool) -> Element -> Element
(define (eliminate-whitespace special eliminate-special?)
  (letrec ((blank-it
            (lambda (el)
              (let ((name (element-name el))
                    (content (map (lambda (x)
                                    (if (element? x) (blank-it x) x))
                                  (element-content el))))
                (make-element
                 (source-start el)
                 (source-stop el)
                 name
                 (element-attributes el)
                 (cond
                   ((eliminate-special? (memq (element-name el) special))
                    (filter (lambda (s)
                              (not (and (pcdata? s)
                                        (or (all-blank (pcdata-string s))
                                            (error 'eliminate-blanks "Element <~a> is not allowed to contain text ~s" name (pcdata-string s))))))
                            content))
                   (else content)))))))
    blank-it))

;; all-blank : String -> Bool
(define (all-blank s) 
  (andmap char-whitespace? (string->list s)))