;; APPEND
(define my-append
  '(lambda-rec (append xs ys) (if (null? xs)
                                  ys
                                  (cons (car xs) (append (cdr xs) ys)))))

(define append-test (list my-append '(cons 1 (cons 2 null)) '(cons 3 (cons 4 null))))

;; MAP
(define my-map
  '(lambda-rec (map proc args) (if (null? args)
                                   null
                                   (cons (proc (car args))
                                         (map proc (cdr args))))))

(define map-test (list my-map '(lambda (x) (* x x)) '(cons 2 (cons 3 (cons 4 null)))))

;; REVERSE
(define my-reverse
  '(lambda-rec (reverse xs) (let (append (lambda-rec (append xs ys) (if (null? xs)
                                                                         ys
                                                                         (cons (car xs) (append (cdr xs) ys)))))
                              (if (null? xs)
                                  null
                                  (append (reverse (cdr xs))
                                          (cons (car xs) null))))))

(define reverse-test (list my-reverse '(cons 1 (cons 2 (cons 3 (cons 4 null))))))

;;TESTY:
;-append
(eval append-test)
;-map
(eval map-test)
;-reverse
(eval reverse-test)