Project Euler #6 in Common LIsp

6.lisp

;;;;
;;;;    6.lisp
;;;;    ProjectEuler
;;;;
;;;;    Created by bitdewy on 4/10/13.
;;;;    Copyright (c) 2013 bitdewy. All rights reserved.
;;;;
 
;; Project Euler #6
(defun square (x)
  (* x x))

(defun sum_of_natural_numbers (max)
  (do ((result 0) (i 0 (1+ i)))
    ((> i max) result)
    (setf result (+ result i))))

(defun sum_of_natural_numbers_square (max)
  (do ((result 0) (i 0 (1+ i)))
    ((> i max) result)
    (setf result (+ result (square i)))))

(- (square (sum_of_natural_numbers 100)) (sum_of_natural_numbers_square 100))