(define map (lambda (f xs)
(let ((accmap (lambda (acc xs)
(if (eq xs nil)
acc
(accmap (cons (f (car xs)) acc) (cdr xs))))))
(reverse (accmap nil xs)))))
(eq (map (lambda (x) (+ x 1)) (list 1 2 3 4 5 6)) (list 2 3 4 5 6 7))