[racket] message passing

From: Jos Koot (jos.koot at telefonica.net)
Date: Sun Aug 8 15:10:55 EDT 2010

May be we can help better with a reference to the exercise.
I really can't make up what you are trying to do.


From: users-bounces at racket-lang.org [mailto:users-bounces at racket-lang.org]
On Behalf Of iam_here at aol.in
Sent: 08 August 2010 19:20
To: users at racket-lang.org
Subject: [racket] message passing

Hello schemers 

what if I have program of massage passing and I have to return the object
when it is defined.

(define (single-order)
(let (
(delivery #f)
(define (the-order req)
(cond ((eq? req 'available)  available)
(else (error "the-order: unknown req: " req))

(define (available)
(set! delivery #t))


(define (available object)
((object 'available)))

=> now when I will run it like

(define mcdon(single-order))

- it should return mcdon instead of <#unspecified>

Any ideas?? 

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