[racket] problem in working out (contents card)

Hello I have a program consists of two tasks. My first task works fine. In second task I have to create a new chip as soon as the new card has been created. I am giving you sample run for the idea ==> (define c1 (a-chip)) c1 ==> (contents c1) 0 ==> (charge c1 10.00) done ==> (contents c1)

[racket] (no subject)

Hello I have a program consists of two tasks. My first task works fine. In second task I have to create a new chip as soon as the new card has been created. I am giving you sample run for the idea ==> (define c1 (a-chip)) c1 ==> (contents c1) 0 ==> (charge c1 10.00) done ==> (contents c1) 1

[racket] message passing

Hello schemers what if I have program of massage passing and I have to return the object when it is defined. example- (define (single-order) (let ( (delivery #f) ) (define (the-order req) (cond ((eq? req 'available) available) (else (error "the-order: unknown r