Play with Emacs Lisp

hello-emacs-lisp.el

;;; filename: emacs-lisp-basic.el

(+ 23 3)
(message "hi")

;; store variable
(setq my-name "Chunyang Xu")
(setq my-age 21)

(insert "hello" " world")

;; define function
(defun hello (name)
  (insert "hi" " " name)
  )
;; call it
(hello "you")hi you

(switch-to-buffer-other-window "xcy.org")

;; combine statements
(progn
  (hello "you")
  (message "date"))

(progn
  (switch-to-buffer-other-window "xcy.org")
  (erase-buffer)
  (hello "there")
  )

;; local variable
(let ((local-name "you"))
  (switch-to-buffer-other-window "xcy.org") ;no need for progn here, let does it
  (hello local-name)
  (other-window 1)
  )

;; format string
(format "I'm %s, %d old.\n" my-name my-age)

(defun hello (name)
  (insert (format "hi %s\n" name)))

(hello "xcy")hi xcy

;; create a function use 'let'
(defun say-hi (name)
  (let ((tmp-message "你好"))
    (insert (format "%s, %s!"
                    name                ;function's argument
                    tmp-message       ;let-bound variable
                    )))
)

(say-hi "徐春阳")


;; 交互式的函数
(read-from-minibuffer "姓名: ")

;; within function
(defun say-hi2 ()
  (let ((name (read-from-minibuffer "姓名 ")))
    (insert (format "\nhi, %s\n" name))))

(say-hi2)
hi, xcy

(defun say-hi-on-other-window ()
  (let (your-name (read-from-minibuffer "姓名 "))
    (other-window 1)
    (insert (format "\nhi, %s" your-name))
    (other-window 1)
    ))

(say-hi-on-other-window)

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; 列表
(setq list-of-numbers '(-2 23 1024))
(setq list-of-names '("me" "my broken ❤"))

;; 第一个
(car list-of-numbers)
(car list-of-names)

;; 剩下的
(cdr list-of-numbers)
(cdr list-of-names)

;; push 添加到开头
(push "chunyang" list-of-names)

;; 注意，car 和 cdr 不会改动列表，而 push 会

;; 映射
(mapcar 'hello list-of-names)

(defun replace-chunyang-by-xcy ()
  (get-buffer-create "new-buffer")
  (switch-to-buffer-other-window "new-buffer")
  (goto-char (point-min))
  (while (search-forward "chunyang")
    (replace-match "xcy"))
  (other-window 1)
  )


(replace-chunyang-by-xcy)

(defun boldfy-names ()
  (switch-to-buffer-other-window "new-buffer")
  (goto-char (point-min))
  (while (re-search-forward "xcy" nil t)
    (add-text-properties (match-beginning 1)
                         (match-end 1)
                         (list 'face 'bold)))
  (other-window 1)
  )

(boldfy-names)

;; lambda

((lambda (name)
   (message (format "hi, %s" name)))
 "Chunyang Xu"
 )


(mapcar (lambda (s) (insert s "\n" ))
        (split-string (shell-command-to-string "ls ."))
)

;; fix the mac PATH variable
(defun ome-set-exec-path-from-shell-PATH ()
  (let ((path-from-shell (shell-command-to-string "$SHELL -i -c 'echo $PATH'")))
    (setenv "PATH" path-from-shell)
    (setq exec-path (split-string path-from-shell path-separator))))

(shell-command-to-string "$SHELL -i -c 'echo $PATH'")