ok

main.rkt

@@ -0,0 +1,80 @@
+(module gregor-utils racket/base
+  (require (prefix-in g: gregor)
+           (prefix-in g: gregor/time)
+           tzinfo
+           racket/string
+           )
+
+  (provide date->moment
+           moment->date
+           racket-date?
+           )
+
+  (define (date*->moment dt)
+    (unless (date*? dt)
+      (error "dt must be of type date*"))
+    ;; As date* will be localtime or UTC, we're working
+    ;; with what we got. We can recognize UTC, but the
+    ;; timezone name will be something OS specific, e.g.
+    ;; on a dutch windows system: West-Europa (zomertijd)
+    ;; which is reported e.g. by windows powershell command
+    ;; get-timezone:
+    ;;
+    ;; Id                         : W. Europe Standard Time
+    ;; DisplayName                : (UTC+01:00) Amsterdam, Berlijn, Bern, Rome, Stockholm, Wenen
+    ;; StandardName               : West-Europa (standaardtijd)
+    ;; DaylightName               : West-Europa (zomertijd)
+    ;; BaseUtcOffset              : 01:00:00
+    ;; SupportsDaylightSavingTime : True
+    ;;
+    ;; but, as the racket standard date functions only
+    ;; work with UTC and localtime, we can request the current timezone
+    ;; tzinfo's (system-tzid) for localtime
+    ;; and use UTC for univeral time.
+    (let ((dt-tz (string-downcase (string-trim (date*-time-zone-name dt)))))
+      (g:moment (date-year dt)
+                (date-month dt)
+                (date-day dt)
+                (date-hour dt)
+                (date-minute dt)
+                (date-second dt)
+                (date*-nanosecond dt)
+                #:tz (if (string=? dt-tz "utc")
+                         "UTC"
+                         (system-tzid))
+                )
+      )
+    )
+
+  (define (date->moment dt)
+    (if (date*? dt)
+        (date*->moment dt)
+        (g:moment (date-year dt)
+                  (date-month dt)
+                  (date-day dt)
+                  (date-hour dt)
+                  (date-minute dt)
+                  (date-second dt)
+                  #:tz (date-time-zone-offset dt)))
+    )
+
+  (define (moment->date m)
+    (make-date* (g:->seconds m)
+               (g:->minutes m)
+               (g:->hours m)
+               (g:->day m)
+               (g:->month m)
+               (g:->year m)
+               (g:->wday m)
+               (g:->yday m)
+               #f
+               (g:->utc-offset m)
+               0
+               (g:->timezone m)
+               )
+    )
+
+  (define (racket-date? dt)
+    (date? dt))
+
+  ); end of module