(filter-visible-calendar-holidays): Test for nil date.
;; This collection of functions implements the features of calendar.el and
;; diary.el that deal with the French Revolutionary calendar.
-;; Technical details of the French Revolutionary calendrical calculations can
-;; be found in ``Calendrical Calculations, Part II: Three Historical
-;; Calendars'' by E. M. Reingold, N. Dershowitz, and S. M. Clamen,
-;; Report Number UIUCDCS-R-92-1743, Department of Computer Science,
-;; University of Illinois, April, 1992.
+;; Technical details of the Mayan calendrical calculations can be found in
+;; ``Calendrical Calculations, Part II: Three Historical Calendars''
+;; by E. M. Reingold, N. Dershowitz, and S. M. Clamen,
+;; Software--Practice and Experience, Volume 23, Number 4 (April, 1993),
+;; pages 383-404.
;; Comments, corrections, and improvements should be sent to
;; Edward M. Reingold Department of Computer Science
;; Technical details of the Mayan calendrical calculations can be found in
;; ``Calendrical Calculations, Part II: Three Historical Calendars''
;; by E. M. Reingold, N. Dershowitz, and S. M. Clamen,
-;; Report Number UIUCDCS-R-92-1743, Department of Computer Science,
-;; University of Illinois, April, 1992.
+;; Software--Practice and Experience, Volume 23, Number 4 (April, 1993),
+;; pages 383-404.
;;; Code:
;; Software--Practice and Experience, Volume 20, Number 9 (September, 1990),
;; pages 899-928. ``Calendrical Calculations, Part II: Three Historical
;; Calendars'' by E. M. Reingold, N. Dershowitz, and S. M. Clamen,
-;; Report Number UIUCDCS-R-92-1743, Department of Computer Science,
-;; University of Illinois, April, 1992.
+;; Software--Practice and Experience, Volume 23, Number 4 (April, 1993),
+;; pages 383-404.
;; Hard copies of these two papers can be obtained by sending email to
;; reingold@cs.uiuc.edu with the SUBJECT "send-paper-cal" (no quotes) and
(let ((visible)
(p l))
(while p
- (if (calendar-date-is-visible-p (car (car p)))
- (setq visible (append (list (car p)) visible)))
+ (and (car (car p))
+ (calendar-date-is-visible-p (car (car p)))
+ (setq visible (append (list (car p)) visible)))
(setq p (cdr p)))
visible))