Shift list elements in Lisp

In continuation to the post "Shift list elements in Prolog". Implementation in Lisp:

(defun lshift (l) (append (cdr l) (list (car l))))

(defun rshift (l)
  (cond
    ((null l) nil)
    ((null (cdr l)) l)
    (t
      ((lambda (r) (cons (car r) (cons (car l) (cdr r))))
        (rshift (cdr l)))
    )
  )
)