[REBOL] Re: What language am I looking for?
From: joel:neely:fedex at: 17-May-2001 8:06
GS Jones wrote:
> Joel, that was a very nice analysis and discussion.
> I learned quite a bit. Thanks.
> Just one question right up front: have you mentioned
> recently that you like REBOL? ;-)
Obviously not recently enough! ;-)
I'm probably overly sensitive on this point, but some of my
attempts at discussing REBOL features, performance, and
trade-offs several months back seemed to provoke some
REBOL, love it or leave it!
responses. Therefore, I try
hard to make clear that my comments and questions are offered
in the spirit of trying to understand and (occasionally)
suggest improvements, not in a spirit of negativity.
I certainly do *not* want to offend anyone on the list or
at RT, nor fail to show appreciation for everything that's
been accomplished to date.
> From: "Joel Neely"
> <big snip>
> > I'm very interested to see if anyone can suggest any
> > others... implementation strategies,
> > not properties of the "source code" notation.
> The strategy that I was chewing on yesterday would probably
> only make a small, incremental difference at best... It
> would seem that there would be at least a small performance
> hit with parsing longer "words" (using the REBOL parlance)
> as opposed to shorter, and that the performance hit
> is additive in loops. I think that I've read that one of
> the first tasks that some compilers undertake is to create
> its own shortened variable name list...
As you correctly state, this is a "compile time" issue. The
closest analog in REBOL is "load time". I suspect that once
a REBOL block has been loaded (converted from external string
form into an internal data structure) that the words are
actually represented by pointers into a context. If that is
correct, then run-time access to the word is a constant-time
operation with no dependence on the name length.
Of course, the construction of a new context requires some
sort of handling of names (or at least pointers to names).
REBOL functions/processes that do this include FUNC (and
it's siblings FUNCTION and MAKE FUNCTION!), MAKE OBJECT!,
However, even if we drove the time for those operations to
zero, it wouldn't speed up most running REBOL scripts by
You might be amused to know that early implementations of
FORTH had a related technique which often tripped up newbie
FORTH programmers. (Remember that FORTH was a truly tiny
language, capable of being implemented in a 4k-8k footprint
on most microprocessors. Saving memory space was even more
of an issue than speeding word lookup.) A common technique
for storing word names in a dictionary was to use the first
three characters of the word and a one-byte length. This
meant that it was all to easy to accidentally create name
collisions, such as
first -> "fir" 3
firms -> "fir" 3
You can image the possibilities for bug-breeding!
Programming languages: compact, powerful, simple ...
Pick any two!