Lisp

1. root
2. command
- 2.1. execute
3. List
4. Evaluation
5. Buffer
6. let and let *
7. Special Form
8. 2-36 arbitrary base
9. code
10. Emacs lisp programm
- 10.1. file management
11. Function in orgmode

1. root

S-express can be atmo or list car : get the first S-express cdr : get the rest list cons : need a S-express and a list : put the first S-express into the second list (null? l) if l is null? (atom? l) if l is atmo? (member? ele list) (rember ele list)

2. command

2.1. execute

command	explain
C-c C-e	result in minibuffer
C-j	result under the cursor
M-x ielm	in elisp interactive mode

3. List

(concat "abd" "def")
(+ 34 9)

(substring "0123456789" 2 8)

(setq Emacs 'My-favour)

(message "Am today %s I start to learn emacs %d " "niaho" 09)
;"Am today niaho I start to learn emacs 9 "
(message "He saw %d %s"
(- fill-column 32)
(concat "red "
(substring
"The quick brown foxes jumped." 16 21)
" leaping."))
;"He saw 38 red foxes leaping."
(setq trees '(pine fir oak maple)
           herbivores '(gazelle antelope zebra))

4. Evaluation

#+BEGIN_SRC elisp

(buffer-file-name) (setq a 300) (* 34 67 45 #+END_SRC)

5. Buffer

(buffer-name)

(current-buffer)

(other-buffer)

(switch-to-buffer (other-buffer))

(buffer-size)

(point)

(point-min)

(point-max)

(defun multipy-by-seven (number)
"Multipy NUMBER by seven"
(* 7 number))

(multipy-by-seven 4)

(defun multipy-by-seven (number))

(interactive "p")

(message "the result is %d" (* 7 number))

6. let and let *

let define the local variable

(defun circle-area (radix)
  (let ((pi 3.1415926)
        area)
    (setq area (* pi radix radix))
    (message "直径为 %.2f 的圆面积是 %.2f" radix area)
    ))
(circle-area 5)

let* define local variable, which can be immediately used

(defun circle-eara (radix)
  (let* ((pi 3.1415926)
         (area (pi*radix*radix))))
    (message "直径为 %.2f 的圆面积是 %.2f" radix area))
(circle-area 6)

7. Special Form

7.0.1. defun

(defun name-of-function (argument-list) "documentation…" body…)

7.0.2. let

(let ((zebra "stripes") (tiger "fierce")) (message "One kind of animal has %s and another is %s." zebra tiger))

7.0.3. if

(defun my-max (a b)
  (if ( > a b)
    (message "aaaaa")
    (message "bbbbb")
    ))
(my-max 3 0)

(if true-or-false-test action-to-carry-out-if-the-test-returns-true)

7.0.4. if-then

(if true-or-false-test action-to-carry-out-if-the-test-returns-true action-to-carry-out-if-the-test-returns-false)

(if 4 'true 'false)

(if nil 'true 'false)

7.0.5. save-excursion

(message "We are %d characters into this buffer." (save-excursion (- (point) (goto-char (point-min)) (point))))

8. 2-36 arbitrary base

#36re
#36r1
#36ra
#36ru
#36rk

9. code

char count

(defun cheap-count-words()
  (interactive)
  (let ((words 0))
    (goto-char (point-min))
    (while (forward-word)
      (setq words (1+ words)))
    (message (format "Words is Buffer : %s" words))
    words)
  )

10. Emacs lisp programm

10.1. file management

read file :: insert-file-contents and copy file :: write-region

;;read file and print out
(defun read-file-as-lines (file-path)
  (with-temp-buffer
    (insert-file-contents file-path)
    (split-string (buffer-string) "\n" t)))

(read-file-as-lines "~/Desktop/110.py")

;;read file and copy to another
(defun copy-file-to-file (fromfile tofile)
  (with-temp-buffer
    (insert-file-contents fromfile)
    (setq copy-test-path tofile)
    (write-region (point-min) (point-max) copy-test-path)
    (write-region "new  content" nil copy-test-path t)))

(copy-file-to-file "~/Desktop/110.py" "~/Desktop/112.py")

11. Function in orgmode

(+ 45 65)

(defun do-some-math(x y)
  (* (+ x 20)
     (- y 10) ) )

(defun multipy-many  (x &rest operands)
  (dolist (operand operands) 
    (when operand 
      (setq x (* x operand)))) x)

interactive function als commands

(defun my-first-command()
(interactive)
(message "Hey , it works") )