Language categories

[David Basil Wildgoose]

Neelakantan Krishnaswami <neelk at cs.cmu.edu> wrote in message news:<slrnbl6r4u.vld.neelk at gs3106.sp.cs.cmu.edu>...
> REBOL is more interesting. The original interpreter was written by Joe
> Marshall, and he wrote it so that it supported lexically-scoped
> closures (and maybe tail-recursion too?). This makes it count as an
> fpl, in my book. However, the second version was a rewrite that lost
> those features, and as a result it's not an fpl anymore.

I have to disagree.  Here's what is said at the REBOL site
(www.rebol.com):

"Although REBOL is designed for easy learning, it excels in sheer
power. Under the hood (for experts) the REBOL engine is a first class,
functional, symbolic language with a rich selection of built-in
datatypes, object support, incremental refinement, integrated
networking, and automatic storage management. In addition, REBOL is
its own reflective meta language."

Note key words and phrases like "functional" and "reflective meta
language".

Also, the original inventor of REBOL is Carl Sassenrath, (yes, the
Amiga guy).

You're right that the second version is no longer tail-recursive, but
that is a matter for the compiler, not the language, and could just as
easily be levelled at the early Lisp implementations.

I would hazard a guess that Rebol's closest relative is probably
Scheme, so I suppose the opinions of most people will be based upon
whether they consider Scheme to be functional.