List Manipulation

(defparameter *list* 0 :one "two" (make-hash-table) 'three)
;; first (car), second, third, tenth ... (nth n list)

(first *list*)

;; rest (cdr)
(rest *list*)

(rest '(1 2 3)) = (2 3)

;; last, butlast
(last '(1 2 3)) = (3)
(first (last *list*))

(alexandria:last-elt *list*)

(butlast *list*)
(butlast '(1 2 3)) = (1 2)

(nthcdr 2 *list*)

Add elements to a list, set elements.

(defparameter *my-list* (list 0 1 2))

(push :thing *my-list*)     ;; push at the first place
(pop *my-list*)             ;; take at the first place
(pushnew :thing *my-list*)  ;; will only push a new element if it doesn't exist

(list* arg &rest others)
(list* :thing *my-list*)
;; add a few elements in front of a list

;; typical idiom: push + reverse
;; instead of appending to the end.
(let ((list (list)))
    (dotimes (i 10)
    (push i list))
    (reverse list))

(loop :for i :upto 10 :collect i)

;; set elements of a list
(setf (nth 1 *list*) :changed!)

(append (list 1 2 3) (list 10 20 30))

(concatenate 'list (list 1 2 3) (list 10 20 30))

Using QUOTE is not the same as LIST function

DANGER: when you think that using QUOTE as in '(1 2 3) is like creating a list with the LIST function '(1 2 3) is not like (list 1 2 3)

(defun supposedly-constant-data ()
  ;; DON'T
  '(1 2 3))

;; sometmes later...
(setf (first (supposedly-constant-data)) 99)

;; we do not have constant data, it does not create a new list but references the same one

(defun constant-data ()
  (list 1 2 3))
;;  ^^ fresh list constructor

(setf (first (constant-data)) 99) ;; OK!
;;               ^^ fresh list