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From: Simon Wright <simon@pushface.org>
Newsgroups: comp.lang.ada
Subject: Re: S-expression I/O in Ada
Date: Wed, 25 Aug 2010 23:38:54 +0100
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Date: 2010-08-25T23:38:54+01:00
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Georg Bauhaus <rm.dash-bauhaus@futureapps.de> writes:

> On 25.08.10 20:55, Simon Wright wrote:
>> Georg Bauhaus <rm-host.bauhaus@maps.futureapps.de> writes:
>> 
>>> To store data, keep the List type, but store objects inside a map.
>> 
>> This would mean that the order in which data is accessed isn't the order
>> in which it was received.
>
> Why not? If reading appends to a list stored at
> the current key which lives on top of a stack?
>
> (A B (C D E) F)
>
> '(' ~> push key_1     -- First key will be returned
>
> key_1 : A B key_2     -- '(' ~> push key_2
> key_2 : C D E         -- ')' ~> pop (key_1 on top)
>  |
>  v
> key_1 : A B key_2 F   -- ')' ~> pop (stack empty)
> key_2 : C D E
>
> First_Key := key_1;
> return;

Oh. I had quite misunderstood your meaning.

There are issues - like copying a sexp and then deleting or changing
part of one of them, how to know when to delete or duplicate.

Seems to me that the key is a disguised pointer to a shared structure?