loop question - scheme help needed

[Alexander Taranov <tay@xxxxxxxxxx>]

Bas Peters writes:
 > Sorry for this basic Scheme question.
 > 
 > If have the following code:
 > 
 > ; removes trailing punctuation for last string character
 > (define (strip-trailing-punctuation s)
 >   (let ((sl-1 (- (string-length s) 1)))
 >     (case (string-ref s sl-1)
 >       ((#\space #\: #\; #\, #\.) (substring s 0 sl-1))
 >       (else s))))

(define (strip-all-trailing-punctuation s)
  (let loop ((s s)
             (sl-1 (- (string-length s) 1)))
        (if (< sl-1 0) "" ;; string contains punctuations only
	(case (string-ref s sl-1)	
	  ((#\space #\: #\; #\, #\.)
           (loop (substring s 0 sl-1) (- sl-1 1)))
          (else s)))))

 > 
 > (define (*extent*)
 >   ; Set x to the MRCB300-a content
 >   (let ((x
 > 	 (data (select-elements (descendants (if (equal? (gi) "MRCB300")
 > 					      (current-node)
 > 					    (ancestor "MRCB300")))
 > 				'(MRCB300-a)))))
 >                  (strip-trailing-punctuation x)))
 > 
 > What I would like to do is to evaluate string -1 untill the condition is
 > false. I tried to use let loop, but it seems to evaluate the string only
 > once. My goal is not only to strip: "bla bla.", but also "bla bla. :"
 > into "bla bla"
 > 
 > Thanks in advance,
 > 
 > Bas Peters
 > bpeters@xxxxxx
 > 
 > 
 > 
 > 
 > 
 >  DSSSList info and archive:  http://www.mulberrytech.com/dsssl/dssslist
 > 


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