This Text file is old! In a 🏛️Museum, an unsorted archive of (user-)pages. (Saved from Geocities in Oct-2009. The archival story: oocities.org)
--------------------------------------- (To 🚫report any bad content: archivehelp @ gmail.com)

; filefilter1.scm - 

(load "readintolist1.scm")

(define (get-rollup line)
      (string->number (regexp-replace* " " (substring line 0 4) "0") 10))

; for fields padded with spaces, replace spaces with zeroes
(define (unpad-number field)
   (regexp-replace* " " field "0"))

(define (add-crlf line)
   (string-append line (string #\return #\newline) ))

(define (filter-file-rollup threshhold infilename outfilename)
   (let ((in-port (open-input-file infilename))
         (out-port (open-output-file outfilename 'replace)))
      (read-test-write threshhold in-port out-port) ))

(define (read-test-write threshhold in-port out-port)
   (let ((line (read-line in-port)))
      (cond 
         ((eof-object? line) (void))
         (else 
	    (let ( (rollup (get-rollup line)) ) 
               ;(display (format "~%rollup: ~A" rollup))
	       (if  (>= rollup threshhold) 
                  (display (format "~A" (add-crlf line)) out-port))
               (read-test-write threshhold in-port out-port) )))))

;---------------------------------------------------------------------
; run program:

(filter-file-rollup 10 "dirlisting2.txt" "temp.txt")
(file-reverse "temp.txt" "dirlisting_10.txt")

(filter-file-rollup 100 "dirlisting2.txt" "temp.txt")
(file-reverse "temp.txt" "dirlisting_100.txt")