jiyoo

(setq aa (vector 10 11 12))
(defun foo (bb)
  (setf (elt bb 0) (+ 90 9))
  (setq bb 9999))
(foo aa)
(print aa) ; => [99 11 12]

jiyoo

(require 'cl-lib)
(defun m-random-choice (seq)
  (elt seq (random (length seq))))
(defvar m-doors (list 1 2 3))

;; baseball scenario:
(cl-loop repeat 10000
         for car-door = (m-random-choice m-doors)
         for chosen-door = 1 ; door chosen by you
         for hit-door = (m-random-choice m-doors) ; door hit by the baseball

jiyoo

;;; Example 4

'(wxyz xy xy-xy end)
'(aabb ab ab-ab end)

(progn
  (font-lock-add-keywords
   nil
   `(("\\bxy\\b"
      (0 'success t))

jiyoo

;; copy the following and
;; paste it in your emacs init file (the dotemacs file)

(defun fix-quotes (beg end)
  "replaces pretty quotes to ugly quotes."
  (interactive "r")
  (save-excursion
    (format-replace-strings '(("\x2019" . "'")
                              ("\x201c" . "\"")
                              ("\x201d" . "\"")