Elisp: Sequence. First, Rest, Nth

get nth element. (index start at 0)

similar to elt

(seq-elt [0 1 2 3] 2)
;; 2

get the first element

(seq-first [3 4 5])
;; 3

return the rest elements.

(seq-rest (vector 3 4 5))
;; [4 5]

(seq-rest (list 3 4 5))
;; (4 5)

;; demo that it return a new copy
(let (xa xb)
  (setq xa (list 3 4 5))
  (print (format "xa is %s" xa))
  (setq xb (seq-rest xa))
  (print (format "xb is %s" xb))
  (pop xb)
  (print (format "xb is %s" xb))
  (print (format "xa is %s" xa)))

;; "xa is (3 4 5)"
;; "xb is (4 5)"
;; "xb is (5)"
;; "xa is (3 4 5)"

(seq-remove-at-position SEQUENCE N)

remove item at index n.

(seq-remove-at-position [3 4 5] 1)
;; [3 5]