working

(defun make-exp (x op y)
  (funcall op x y))

(defun eek (exp)
  (cond ((null (second exp)) exp)
        ((and (listp (first exp)) (listp (third exp)))
         (make-exp (eek (first exp)) (second exp) (eek (third exp))))
        ((listp (first exp)) (make-exp (eek (first exp)) (second exp) (third exp)))
        ((listp (third exp)) (make-exp (first exp) (second exp) (eek (third exp))))
        (t (make-exp (first exp) (second exp) (third exp)))))

(defun listify (exp)
  (if (endp (cdr exp))
      (car exp)
      (list (car exp) (cadr exp) (listify (cddr exp)))))

(defun listify-2 (exp)
  (cond ((endp (cdr exp)) (car exp))
        ((listp (car exp)) (list (listify-2 (car exp)) (cadr exp) (listify-2 (cddr exp))))
        (t (list (car exp) (cadr exp) (listify-2 (cddr exp))))))

(defun naive-infix (exp)
  (let ((listified (listify-2 exp)))
    (print listified)
    (eek listified)))

(naive-infix '(1 + (2 * (12 / 3) + 6) - 4))