[plt-scheme] structure consist of list.

From: John Clements (clements at brinckerhoff.org)
Date: Tue Nov 24 22:54:04 EST 2009

On Nov 23, 2009, at 5:58 AM, Mona wrote:

> Hi everybody
> I have one question about define struct that consist of list.
> (define-struct trading-card (card-number name role))
> ;trading-card is a structure (make-trading-card c-n n r)
> ;where c-n is number and n , r are string.
> ;Example
> (define trading-card1(make-trading-card 1 'PEZZE 'FULL))
> (define trading-card2(make-trading-card 7 'LANZA 'ASSOCIATE))
> (define trading-card3(make-trading-card 16 'POZZI 'ASSISTNT))
> (define-struct pack (tradinging-card))
> ;pack is a structure (make-pack t-c)
> ;where t-c is a list of trading-card.
> (define pack1(make-pack (list trading-card1 trading-card2 trading-
> card3)))
> I want to say  get the structure of the pack (that consist of the
> list) and if trading-card-card-number < 5 return true but I dont know
> how to do in SCheme?
> (make-pack
> (list
>  (make-trading-card 1 'PEZZE 'FULL)
>  (make-trading-card 7 'LANZA 'ASSOCIATE)
>  (make-trading-card 16 'POZZI 'ASSISTNT)))

Nice examples!

Unfortunately, you're missing the one example that would help figure  
out what it is that you want.  In particular, are you trying to  
determine whether the *first* card in the deck has a number less than  
five, or whether *all* of the cards have numbers less than five, or  
whether *any* of the cards have a number less than five, or...?

Put differently: it looks like you're following the design recipe:  
keep following it!

John Clements

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