Re: Be afraid of XML

From: Pete Kirkham (pete-kirkham-2004_at_cafemosaic.co.uk)
Date: 03/12/04 

Date: Fri, 12 Mar 2004 00:30:31 +0000

It takes a particular kind of paranoia that you think someone's ironic
response to a mis-application of a technology is an application of said
technology (the point of the article was it's a stupid idea to put JVM
stack traces into XML syntax, so exaggerate the concept and put the
whole of the JVM into XML). But then someone here believed the spoof XML
encoding of bits as well.

Please try and remember
- not everyone who uses lingua-franca technologies is an idiot
- not everyone on the planet writes in languages that can be encoded in
  the ASCII charset, so delimited Unicode for marking up text is hardly evil
- if using a tree structure represented by delimited text for data is
bad, why are you using lisp?
- it is possible to map s-expressions to a subset of the XML infoset, so
anything you do with s-expr is just XML with minor syntactic differences
(around 5% smaller size for a loss of some syntactic redundancy for
textual applications, data-intensive are better done in binary anyway
once debugged in a textual format). This also means that there is 50
years prior art for any patent for XAML or XUL as programming language
(or at least as far back as the first lisp WIMP GUI).
- XML is a general tree syntax suitable for world-wide use. XML is a
pruned scion of SGML so it has angle brackets and closing tags (if you
are marking up text, then you don't want to escape every parenthesis).
Is <para id="foo">Hello World</para> so much worse than (para :id "foo"
:text "Hello World")? Is the idea of using an application independent
reader so bad (SAX)? or allowing arbitrary declarative transformations
of the resulting parse tree (XSLT) expressed in the same syntax, so the
code and the data are one? Yes, XML's ended up doing most the same
things as s-expr, the lisp reader and macros did, but on the web, in the
same syntax family as an enormously popular document markup language.

If s-expr are so much better as an interchange language, then make apps
that integrate with the existing infrastructure and have improved
capabilities over their XML counterparts.

It is easier to write '(apply #'+ '(1 2 3)) than the math-ml equivalent,
but there isn't a standard for integrating that as a display language in
a browser, nor standard s-expr symbols for most of the symbols in
math-ml. So why isn't s-expr being used as a human interface language
for math on the web? If the syntax mattered, and the symbolic algebra
community are aware of lisp, then shouldn't there already be s-expr
interfaces for math-ml. Instead, each math package exports to a common
standard, and as the need for integrating with html (otherwise export to
TeX) is important, the syntax of this common standard is in the same family.

Why is OWL being used when it's not as capable as KIF*? KIF is s-expr,
and designed for interchange. Neither have to be directly displayed in a
browser. But KIF doesn't fit in with the existing web toolset, and
people seem willing to add to the SG/HT/X-ML syntax family rather than
integrate different ones- even though much of semweb is coded from
scratch, and in lisp as often as not. But to use KIF on the web, you
have to munge all case-sensitive URIs and escape Unicode; so it has
"does not play well with others" on its report card. As with the main
declarative XML languages (XHTML, XSD, XSLT, MathML, SVG, XForms),
having the programming language in the same syntax as the data is seen
as an advantage, just as in lisp.

In terms of technology, syntax doesn't matter; in terms of how easily a
user can interact with a language, it does. The current crop of code
cutters grew up with HTML. People can relearn given incentives, but some
of the postings here are bugs caused by parenthesis nesting.

I think that selling a 21st century lisp which uses s-expr as an
abbreviated XML has mileage. Or a direct XML encoding of lisp s-expr as
a 'web programming language'. Allow the same abstract tree to be encoded
as s-expr, XML, ASN.1, RDBMS tables for coding, browser integration,
data exchange and persistence. Let the web monkeys use XML until they
know how to match the parentheses. Map the object system to and from UML
in an explicit manner, and provide model-driven, pattern based and
aspect oriented programming as language level facilities. In a couple of
years, almost everyone will be using a single dispatch bytecode
environment (CLR, if not Java). Make a lisp that accepts that limitation.

Sometimes the people here (and in the XML world) sound like it actually
matters how pointy the delimiters in the syntax are. Get over it, and
work the technology at the abstract level, not the text. S-expr are a
syntax that represents an abstract tree. So is XML. Use the acceptance
of standard readers and macro languages to take lisp further. Use the
experience of the lisp community to not reinvent technologies, with only
a syntax change.

Pete

* actually the use cases for the semantic web indicate that OWL is
closer to being in the same niche as EXPRESS rather than KIF, though it
never seems to be compared to it; possibly because getting applications
to exchange information reliably using a common information model isn't
as sexy as a world-wide ontology based artificial intelligence.

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