[exprla-devel] Re: [XPL] Is the project alive?

[reid_spencer <ras...@re...>]

--- In xpl-dev@y..., Jonathan Burns <saski@w...> wrote:
Steve Ball wrote:

> Now, an XML based language is going to be quite verbose.  That's the
> nature of XML.  For that reason it is unlikely that people are
> going to type it in interactively on a command-line, like Tcl.
> It then follows that XPL will be a compiled language.  Is that
> reasonable logic?
>

"Compiled" is getting to be a somewhat fuzzy word in this context.

Traditional compilers (1) translate high-level source to a parse-tree
structure, and (2) address a machine architecture (i386, PPC, 
JVM, ...)
to translate parse-tree traversal into efficient machine code.

For the verbosity issue, we're looking at (1). Standard high-level
languages already give us concise and powerful expression syntaxes.
The question for XPL is, can we smoothly and accurately translate
from these syntaxes to verbose XPL, and back again? IF so, then in
a sense, high-level languages are just styles of one another, and
something like XLST might work as a translator. The REAL technology
for HLL -> XPL is BNF grammars, meaning the ancient Yacc, or 
reasonable
facsimile, as used in hundreds of compiler parsers.

The other compilation issue, (2) is execution speed - to which we must
these days add machine-code size, for swift transmission of executable
code. I reckon that we get most of this, if we just tokenize the XPL
text - a straightforward task.


> There are several reasons why a XML based language is appealing.
> One is that all of the tools being developing for authoring,
> styling and otherwise manipulating XML documents become immediately
> useful to XPL programming.  But are they really useful?

Oh, how I need the study time, to determine the precise answer!

My impression is that almost every XML tool being developed is 
relevant
-
XPath, XLink, the DOM, XSLT, and more. Put them together, and they may
give an enormous initial boost to the XPL effort.

My XPL slogan:

    What can we do WITH an XML document?
    What can we do TO an XML document?

> XSL could be used to style a XPL program.  XSL could also be used to
> generate a XPL program, but would that happen in real life?
>

Alexander Gutman and Richard Hein are interested in this one, and
they'repretty affirmative.

I just want to say:

    Anything that can take high-level syntax and produce a parse-tree
    can produce it in XML text as easily as it can in linked data
    structures.

So, Yes.

> Programs tend to be written, rather than generated, or could XSL
> be used as a macro facility?
>

Yes. But in our enthusiasm for the new tools, let us not neglect
yearsand years of traditional parsing experience. Don't dis the yacc.

This, by the way, is why I like DTDs. Pure grammar.

The question, "DTDs or Schemas?" is one we must trhoroughly explore;
like another one, "DTDs or Namespaces?"  They may both turn out to be
religious, but they must certainly both be addressed in a Real White
paper.

> At the Tcl2K conference I spoke with Dave Beazley about SWIG version
> 2,
> and it is using XML in interesting ways.  Could be some overlap 
there.
>
>

Well, I checked out Zveno last night, and I'm impressed. It pleases
megreatly to have this resource in Australia.

Jonathan

"These are not 'globals', dear boy, these are Total Access Variables.
And they're the coming thing."

"Unleash the Power!"
--- End forwarded message ---