RosettaCodeData/Task/Apply-a-callback-to-an-array/ACL2/apply-a-callback-to-an-array.acl2

(defun apply-to-each (xs)
   (if (endp xs)
       nil
       (cons (fn-to-apply (first xs))
             (sq-each (rest xs)))))

(defun fn-to-apply (x)
   (* x x))