Re: Scripts vs APIs

Linas Vepstas (
Fri, 9 Sep 1994 11:01:32 -0500

> From: (John Ellson)
> To:,,
> Cc:
> Date: Fri, 9 Sep 94 00:14:52 EDT
> > From: (Linas Vepstas)
> >
> ...
> > Think of the differences from the implementors side:
> > memory management -- a named object, once declared, is known to be
> > pointing at a valid group of data of a known size. That's that.
> I would if we had to implement a new language. I guess I was hoping
> we would use an existing language so that the primary concerns could be
> ease of expression for authors, and communications efficiency for
> performance?

Re: expression for authors:
The point is that I'd like the prefered tool be some drag-n-drop,
menu-driven interface. Something my wife could use. Open an
existing file that describes a room with a table, pick "sphere"
from menu, drag it over to the table, and drop it. Viola.

Gavin Bell reminds me that an editor for postscript that can open
up and succesfully edit a pre-existing postscript file is essentially
non-existant. Its just too complicated. Ditto for C. COBOL does
have some primitive tools to do this, but they cost $100K and up.
The COBOL market is bigger and has more money.

May I also remind that virtually nobody writes postsript by hand.
Ditto for AutoCAD DXF files, which are actually a descriptive language.
In the word-processing world, HTML and TeX are about the only two
things people write by hand, rather than with some word-processor.
And HTML is succumbing fast ... while TeX is proceedural.

I suspect that our goals for the language are different. Although
there are word-processors that will animate text, and do slide shows,
and other things, none of them would allow you to specify words that
would fly around a page as if they were a flock of birds. If you want
to do that, you have to use C or maybe write some postscript by hand ...
you certainly cannot do it with HTML.

So do you want to use VRML for complicated VR simulations? Or do you
want it for simple 3D on the net, viewable on lowly 386/486 with
interactive speeds?

> Your knowledge of the differences between declarative and
> procedural languages is out of my reach, so I'm going back
> off and listen for a while. I'm primarily interested in 1) ease of
> expression to an author and 2) efficiency of network use so as to optimize
> communication performance. These don't even have to be
> provided by the same language as far as I can see? I really don't have
> a vested interest in any particular language approach as long as these
> needs are met. It wouldn't bother me if there were translators (or compilers,
> or interpreters) from the author's language, to the interchange language, to
> the rendering language. Compiler and interpreter technologies are
> well developed so I really don't understand the implementation concerns
> that you have, nor do I think they should be of primary concern.

Hmm interesting idea ...

> BTW. Do you have a reference for an example declarative style langauge?
> Perhaps with an ftp'able source?

No ... maybe some textbook on compilers or languages ...

> > Hmmm ... what happens when someone hands you a sphere, and then
> > says, "no, its a cube". Typing has its place ...
> Are we talking about a single VRML interaction with a server, or multiple?
> How did this change of mind take place? Did the author not test the
> VR scene before publishing?

Nah, I was refering to something more mundane ...
float x; int *i; i= &x; (*i) ++; // uhh-ohh.

> John