exam mutating parameters itself

pass-by-ref.scm

;; SEE ALSO
;; http://stackoverflow.com/questions/1080328/append-in-scheme

(define foo '(hello world))
(append! foo '(bar))
(display foo)(newline)


(define my-append!
  (lambda (a . b)
    (if (null? (cdr a))
        (set-cdr! a b)
        (my-append! (cdr a) (car b)))))

(my-append! foo 'my-append)
(display foo)(newline)


(define push
  (lambda (lst . varr)
    (append! lst varr)))

(define mypush
  (lambda (lst . varr)
    (if (null? (cdr lst))
        (set-cdr! lst varr)
        (mypush (cdr lst) (car varr)))))

(push foo 'new 'push 'way)
(display foo)(newline)
(mypush foo 'mypush 'way)
(display foo)(newline)