recipes.org

stream-of-directory-files

stream.el

;; 模仿 ls -R
(defun foo ()
  (interactive)
  (with-current-buffer (get-buffer-create "*LS*")
    (setq buffer-undo-list t)
    (erase-buffer)
    (switch-to-buffer (current-buffer))
    (seq-do
     (lambda (f)
       (insert f ?\n)
       (goto-char (point-max))
       (set-window-point (selected-window) (point-max))
       (redisplay))
     (stream-of-directory-files "~/.emacs.d/" nil 'nosort 'recurse))))

stream-from-iterator

iter-defun is defined in generator.el

(iter-defun fibonacci ()
  (let ((a 0)
        (b 1))
    (while t
      (iter-yield a)
      (cl-psetq a b
                b (+ a b)))))

;; 前 10 个斐波那契数
(cl-loop repeat 10
         for n iter-by (fibonacci)
         collect n)

(-> (fibonacci)
    (stream-from-iterator)
    (seq-take 10)
    (seq-into 'list))

stream-cons

(defun fib (a b)
  (stream-cons a (fib b (+ a b))))

(seq-into (seq-take (fib 0 1) 10) 'list)

stream-range

(seq-into (stream-range 0 5) 'list)

(seq-into (seq-take (stream-range 0) 5) 'list)

stream-scan

(seq-into
 (seq-take (stream-scan #'* 1 (stream-range 1)) 5)
 'list)

map-let

(map-let (x y) '((x . 1) (y . 2))
  (list :x x
        :y y))

(map-let (x y) '((x . 1) (y . 2))
  (list :x x
        :y y))

(map-let (('x a) ('y b)) '((x . 1) (y . 2))
  (list a b))