; testing a function on p183 of Cooke
(defun as ( x y a b)
   (cond
    ((null x) x)
    ((equal (caar x) y)  (eval (list (cadar x) a b) ) )
    (T  (as (cdr x) y a b))
   )
)
(setq m '((add +) (minus -) )); for testing