A tentative slice implementation

dash-slice.el

(defun --slice (list from &optional to)
  "Return copy of LIST, starting from index FROM to index TO.
FROM or TO may be negative"
  ;; to defaults to the end of the list
  (setq to (or to (length list)))
  ;; handle negative indices
  (when (< from 0)
    (setq from (mod from (length list))))
  (when (< to 0)
    (setq to (mod to (length list))))
  (-take (- to from) (-drop from list)))