Way off topic (was: Lisp concrete syntax)

Rick Jelliffe ricko at allette.com.au
Tue Mar 16 23:27:26 GMT 1999

>Not to be a pest or anything, shouldn't this be...
>    <car>+</car>
>    <cdr><car>1</car><cdr><car>1</car><cdr/></cdr></cdr>

There are three things we could be notating:
 * parsing the s-expression source code;
* fully expanding the notional LISP lists;
* exposing the implementation.

The form I gave parses the s-expression. The version you give shows the
fully expanded list. And if an implementation used cdr-coding, it would
look like my version; if it used explicit nulls, it would look like your

This is a good example that XML markup is not a data modeling language,
but a data-model modeling language :-)  The lexical, semantic and
implementation structures of a programming language are all different,
and a XML document could reflect any of them (or even a mix).


P.S. For more on cdr-coding, refer

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