(define-record-type rectangle
  (make-rectangle begin end)
  rectangle?
  (begin   rect-begin )
  (end     rect-end )
  )


;; Whether a point falls within a rectangle, including the rectangle's edges.
(define (in-rect? p r)
  (and (point? p) (rectangle? r)
       (p>= p (range-begin r)) 
       (p<= p (range-end r))))


;; rect-union x y yields the smallest rectangle z such that x ``includes``
;; z and y ``includes`` z.
(define rect-union
  (let ((f (lambda (fl fr)
	     (lambda (a b)
	       (make-rect (fl (rect-begin a) (rect-end b))
			  (fr (rect-begin b) (rect-end b)))))))
    (f pmin pmax)))


;; Yields whether the second argument completely falls within the
;; first argument.

(define (rect-includes? r)
  (and (rectangle? r)
       (lambda (x)
	 (and (rectangle? x) 
	      (in-rect? (rect-begin x) r)
	      (in-rect? (rect-end x) r)))))