range.rkt

#lang scheme
(define range
	(lambda (future_list)
		(if (list? future_list)
			(if (= (car future_list) 0)
				future_list
			;else
				(range (cons (- (car future_list) 1) future_list))
			)
		;else
			(range (cons future_list null))
		)
	)
)