1) XML for markup uses angle brackets and verbose syntax for tags
because it is intended to be used with plain text and should clearly
stand out (and use unusual for plain text characters so you don't have
to escape every parenthesis).
There is no acceptable substitute for TEXT MARKUP based on
s-expressions.
2) The s-exp example of data markup is inadequate,
((a :href "target") "Some text'), not (a (:href "target") ....
3) Anyone who uses either s-expressions or XML markup for manual input
of DATA does a wrong thing. Except for extremely rare cases, both are
crap; and there are better ways to accomplish that. The usefullness of
either XML or S-exp is in consistent processing; both have advantages
and drawbacks for computers, and both are disaster as a format for data
for humans. With s-exp being just a little bit smaller disaster, but
the difference is neglectible.
The main cause for people to enter their data in XML is that they
already familiar with XML as text markup, and their eyes are trained to
perceive it; HTML writers are more frequent than lisp programmers,
after all.
> If it is not intended to be processed manually, then it will
> not need verbose syntax or tags to clearly stand out.
Verbose syntax of tags are for validation by programs, not for manual
processing. Tags must clearly stand out syntactically, so that
validation and processing algorithms detect errors in complex data
structures reliably and recover soon. Recovery in a long tail of
closing parentheses of which one is missing is error-prone (as everyone
who programs in lisp knows well enough).
············@gmail.com wrote:
> Verbose syntax of tags are for validation by programs, not for manual
> processing. Tags must clearly stand out syntactically, so that
> validation and processing algorithms detect errors in complex data
> structures reliably and recover soon. Recovery in a long tail of
> closing parentheses of which one is missing is error-prone (as everyone
> who programs in lisp knows well enough).
>
You mean Lisp programs often don't work because we get the
parentheses wrong??
That happened to me maybe two or three times, and every time I
noticed the error within a minute (just ask the editor).
Also, most XML files are generated automatically anyway. There it
should be trivial to get the matching right.
> > structures reliably and recover soon. Recovery in a long tail of
> > closing parentheses of which one is missing is error-prone (as
everyone
> > who programs in lisp knows well enough).
> >
>
> You mean Lisp programs often don't work because we get the
> parentheses wrong??
>
No, and what I mean is clear from the snippet you've quoted. I mean
that the Lisp reader has no way to know which of the parentheses is
missing because they all are the same, while XML reader detects a
missing one immediately.
This is important for validation in protocols and for algorithmic
recovery in processing.
David
>>>>> "David" == david ······@gmail com <············@gmail.com> writes:
[...]
David> I mean that the Lisp reader has no way to know which of the
David> parentheses is missing because they all are the same, while
David> XML reader detects a missing one immediately.
Very true. Redundancy is not useless.
David> This is important for validation in protocols and for
David> algorithmic recovery in processing.
This of course is a red herring. XML processors are supposed to throw
an error and stop processing as soon as a malformed input is detected
(as I understand it, this is subject of religious infighting among the
XML people but IIRC Mr Bray in that interview defends that decision to
this day). Early detection might be OK and useful to avoid wasting
resources. Recovery is not intended and therefore no defense for
verbosity.
Holger