Adding date->seconds

original commit: 1b6b721aee3bd26c9fcb2cf985815f584e2b20a0

collects/mzlib/date.rkt

@@ -7,6 +7,7 @@
 
 (provide/contract
  [current-date (-> date?)]
+ [date->seconds (date? . -> . exact-integer?)]
  [date->string ((date?) (boolean?) . ->* . string?)]
  [date-display-format (parameter/c (symbols 'american 'chinese 'german 'indian 'irish 'julian 'iso-8601 'rfc2822))]
  [find-seconds ((integer-in 0 61)
@@ -251,6 +252,15 @@
     (lambda ()
       (force d))))
 
+(define (date->seconds date)
+  (find-seconds 
+   (date-second date) 
+   (date-minute date) 
+   (date-hour date) 
+   (date-day date) 
+   (date-month date) 
+   (date-year date)))
+
 (define (find-seconds sec min hour day month year)
   (define (signal-error msg)
     (error 'find-secs (string-append