How to set calendar-date-style in init?

[Pankaj Jangid]

I have tried following options in my init file, but none of them seem to
be working. I have tried with and without /lexical-mode:t/.

I have tried following options. What am I doing wrong here?

--8<---------------cut here---------------start------------->8---
;; option-1
;;(declare-function calendar-set-date-style "calendar.el")
;;(calendar-set-date-style 'european)

;; option-2
;; (custom-set-variables
;;  '(calendar-date-style 'european))

;; option-3
;; (defvar calendar-date-style)
;; (setq calendar-date-style 'european)

;; option-4
(eval-when-compile (require 'calendar))
(setq calendar-date-style 'european)
--8<---------------cut here---------------end--------------->8---