s c h e m a t i c s : c o o k b o o k

> (require (lib "date.ss"))
> (date-display-format 'iso-8601)   
> (date->string (seconds->date (current-seconds)) #t)
"2004-04-28 10:34:19"

(require (lib "string.ss" "srfi" "13")
         (prefix time: (lib "time.ss" "srfi" "19")))
(define (date->iso8601 dt)
  (let ((tzoff (/ (time:date-zone-offset dt) 3600)))
    (format "~A~A~A:~A" 
           (time:date->string dt "~Y-~m-~dT~H:~M:~S") 
           (if (< tzoff 0) "-" "") 
           (string-pad (number->string (abs tzoff)) 2 #\0) 
           "00")))
  
(define (iso8601->date str)
  (time:make-date 0
                  (string->number (substring/shared str 17 19))
                  (string->number (substring/shared str 14 16))
                  (string->number (substring/shared str 11 13))
                  (string->number (substring/shared str 8 10))
                  (string->number (substring/shared str 5 7))
                  (string->number (substring/shared str 0 4))
                  (if (char=? (string-ref str 19) #\Z)
                      0
                      (- (+ (* (string->number (substring/shared str 20 22)) 3600)
                            (* (string->number (substring/shared str 23 25)) 60))))))