Re: even elder races get tired of waiting

[Emanuel Berg]

>> OK? And days start at 00:00?
>
> Good question!
>
> There are few definitions for days, some definitions will
> say it starts at zero, some others will tell it is interval
> of 24 hours, not necessarily starting at zero, and some
> definition will speak of daylight period. [...]

How do you suggest I improve the function?

;;; -*- lexical-binding: t -*-
;;;
;;; this file:
;;;   http://user.it.uu.se/~embe8573/emacs-init/time-cmp.el
;;;   https://dataswamp.org/~incal/emacs-init/time-cmp.el

;; ...

(require 'cl-lib)
(defun days-from-date (d1 d2)
  (let*((sep     "-")
        (d1-data (cl-map 'list #'string-to-number (split-string d1 sep)))
        (d2-data (cl-map 'list #'string-to-number (split-string d2 sep)))
        (y1      (car   d1-data))
        (m1      (cadr  d1-data))
        (d1      (caddr d1-data))
        (y2      (car   d2-data))
        (m2      (cadr  d2-data))
        (d2      (caddr d2-data)) )
    (days-from y1 m1 d1 y2 m2 d2) ))
;; (days-from-date "2021-03-19" "2021-04-20") ; 31

(defun days-from (y1 m1 d1 y2 m2 d2)
  (let*((s-then (float-time (encode-time 0 0 0 d1 m1 y1)))
        (s-now  (float-time (encode-time 0 0 0 d2 m2 y2)))
        (s-diff (- s-now s-then)) )
    (string-to-number (format-seconds "%d" s-diff) )))
;; (days-from 2021 03 19 2021 04 20) ; 31

;; ...

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