C-x v diary-file tells you:
The file’s entries are lines beginning with any of the forms
specified by the variable ‘diary-date-forms’, which by default
uses the forms of ‘diary-american-date-forms’:
MONTHNAME DAY, YEAR
So just do
April 15 ...
The library appt.el contains the variables/functions sought. Consider using something like (require 'appt) before attempting to locate (with functions such as describe-... or find-...) and/or before attempting to use the variables/functions.
Q: How did I find the answer to this question?
A: I grepped the lisp folder (of the Emacs source code) for the ...
diary-sunrise-sunset returns a string with both times:
"Sunrise 6:17am (EST), sunset 5:36pm (EST) at 40.3N, 71.0W (11:19 hrs daylight)"
So use diary-sunrise and diary-sunset separately:
where these two functions are defined as follows (somewhere in your init file):
(defun diary-sunrise ()
(let ((dss (diary-sunrise-...