The Little Schemer

Hi, I am working through the little schemer. I do not have the math skills to work through SICP.

I have the following code:


(define (member? a lat)
  (lambda (a lat)
    (cond
      ((null? lat) #f)
      (else (or (eq? (car lat) a)
                (member? a (cdr lat)))))))


When I run this say like:
(member? 3 (cons 3 '(9 8 7 6 13 3)))

I get the following:
#<procedure:...my-scheme-log.ss:137:2>
rather than a list without the first instance of 3

Can you help me?

I do not understand how this works:


;; define occur such that (occur 1 '(1 2 3 4 1 1 1 5)) -> 4
(define occur
  (lambda (n lat)
    (cond
      ((null? lat) 0)
      ((eqan? (car lat) n) (add1 (occur n (cdr lat))))
      (else (occur n (cdr lat))))))

How can I use (add1) in the way mentioned above when it is defined as:


(define add1
   (lambda (n)
     (+ 1 n)))