;;; -*- lexical-binding: t -*-
;;
;; this file:
;;   https://dataswamp.org/~incal/emacs-init/list.el

(require 'cl-lib)

(defun count-list (l)
  (cl-loop
    with res
    for e in l
    while l
    do (push (list e (cl-count e l)) res)
       (setq l (cl-remove e l))
    finally return (cl-sort res #'>= :key #'cadr)))

;; (count-list '(a b c d e a b c d a b c a b a))
;;   -> ((a 5) (b 4) (c 3) (d 2) (e 1))

(defun result-list (l)
  (cl-loop
    with str = ""
    for (e o) in l
    for i from 1
    do (setq str (format "%s\n%d. %s (%d)" str i e o))
    finally return (string-trim str)))

;; (result-list (count-list '(a b c d e a b c d a b c a b a)))
;;   -> 1. a (5)
;;      2. b (4)
;;      3. c (3)
;;      4. d (2)
;;      5. e (1)

(defun lists (&rest l)
  `(,@l))

;; (lists)                      ; ()
;; (lists '(a b c) '(d e f))    ; ((a b c) (d e f))
;; (lists () '(a) '(b c d e f)) ; (() (a) (b c d e f))

(defmacro pushlast (newelt place)
  (declare (debug (form gv-place)))
  (macroexp-let2 macroexp-copyable-p x newelt
    (gv-letplace (getter setter) place
      (funcall setter `(append ,getter (cons ,x nil))))))

(provide 'list)