1 (defun cube (x)
2   (* x x x))
3 (defun sum (term a next b)
4   (if (> a b)
5       0
6     (+ (funcall term a)
7        (sum term (funcall next a) next b))))
8 (defun sum-integers (a b)
9   (sum #'identity a #'1+ b))
10 (defun pi-sum (a b)
11   (defun pi-term (x)
12     (/ 1.0 (* x (+ x 2))))
13   (defun pi-next (x)
14     (+ x 4))
15   (sum #'pi-term a #'pi-next b))
16 (defun integral (f a b dx)
17   (defun add-dx (x)
18     (+ x dx))
19   (* (sum f (+ a (/ dx 2.0)) #'add-dx b) dx))