(import (rnrs)

(stream)

(utils))

(stream-display (stream-map square (list-stream 1 2 3)))

(stream-display (stream-map + (list-stream 1 2 3) (list-stream 2 3 4)))

list-stream

stream-enumerate-interval

stream-display)

(import (rnrs)

(utils))

(define (memo-proc proc)

(let ((already-run #f) (result '()))

(lambda ()

(if (not already-run)

(begin (set! result (proc))

(set! already-run #t)

result)

result))))

(define (force delayed-object)

(delayed-object))

((cons-stream a b)

(cons a (memo-proc (lambda () b))))))

(define-syntax list-stream

(syntax-rules ()

[(_) the-empty-stream]

[(_ a b ...)

(cons-stream a

(list-stream b ...))]))

; (define (stream-map proc s)

;(if (stream-null? s)

;the-empty-stream

;(cons-stream (proc (stream-car s))

;(stream-map proc (stream-cdr s)))))

; (stream-map proc stream stream ...)

(define (stream-map proc . stream-args)

(if (stream-null? (car stream-args))

(cons-stream (apply proc (map stream-car stream-args))

(apply stream-map (cons proc (map stream-cdr stream-args))))))

(define (stream-display s)

(if (not (stream-null? s))

(begin

(println (stream-car s))

(stream-display (stream-cdr s)))))

divides?

println)

(define (println v)

(display v)(newline))