(eval '(let (oper->proc (lambda (op) (cond [(eq? op (quote add)) +]
                                           [(eq? op (quote sub)) -]
                                           [(eq? op (quote mul)) *]
                                           [(eq? op (quote div)) /])))
         (let (binop-op (lambda (e) (car e)))
           (let (binop-left (lambda (e) (car (cdr e))))
             (let (binop-rght (lambda (e) (car (cdr (cdr e)))))
               (let (eval-arith (lambda-rec (evall expr)
                                            (cond
                                              [(pair? expr) (cond [(eq? (binop-op expr) (quote add)) ((oper->proc (binop-op expr)) (evall (binop-left expr)) (evall (binop-rght expr)))]
                                                                  [(eq? (binop-op expr) (quote sub)) (- (evall (binop-left expr)) (evall (binop-rght expr)))]
                                                                  [(eq? (binop-op expr) (quote mul)) (* (evall (binop-left expr)) (evall (binop-rght expr)))]
                                                                  [(eq? (binop-op expr) (quote div)) (/ (evall (binop-left expr)) (evall (binop-rght expr)))]
                                                                  )]
                                              [true expr])))
                 (eval-arith (cons (quote add) (cons  (cons (quote add) (cons 2 (cons 4 null))) (cons  (cons (quote add) (cons 2 (cons 4 null))) null))))))))))