Re: [stack] the concatenative wikipedia article

pml060912 <[email protected]> wrote:
> "William Tanksley, Jr" <wtanksleyjr@...> wrote:
>> non-associative syntax at all (AKA "flat"). Quotation is a strange
>> thing to throw into an allegedly concatenative combinator base,
>> though; unlike application, it's not an inherent part of the language
>> paradigm; thus, I think my confusion is justified.

> Well, where does Furphy fit in this breakdown?
> (http://users.beagle.com.au/peterl/furphy.html)
> Although it does have quotation, as I mentioned elsewhere that's just
> syntactic sugar. The fundamental constructs are Reverse Polish naming
> and concatenation, which can use the complementary keywords FREEZE and
> THAW to defer and invoke evaluation/execution - and those can be built
> from the return stack manipulation keywords R> and >R already found in
> Forth. That looks fairly associative/flat to me.

Furphy is a fascinating language; I had no idea it had such an
interesting loop system. I'd say that Furphy probably is
flat/completely associative; but note that I'm not sure what to do
with the "Reverse Polish naming" system.

Furphy's loop system isn't strictly needed in order to be completely
associative; a ColorForth-like scheme would also work, where a label
(word name) is identified by a special character, tail recursion is
automatic, and the compiler recognizes the return operator.

For those who don't know ColorForth: Colorforth uses "labels" instead
of having distinct words; unlike Forth, where a word name begins a new
definition (which implies that the old definition is finished), a
ColorForth definition merely implies a new entry point.
Correspondingly, the ";" word in ColorForth compiles a return (which
will normally be optimized to a tail call) rather than strictly ending
the current definition.

ColorForth itself is not flat, because it keeps the concept of
immediate words; however, it would be easy to do the same thing a
Furphy and remove the need for all the immediates.

Unfortunately, Furphy is a foreign language to me, so I can't
understand the discussion of FREEZE and THAW. I think the use of
"Reverse Polish Naming" is blocking my understanding -- I can't tell
when a word I don't recognize is intended to be a definition versus
when it's simply unfamiliar to me. With all due respect, I'm pretty
sure that Reverse Polish Naming isn't a good idea; it's way too easy
to mess a file's semantics up by pre-defining one of the words it
intends to define. I'd far rather make definitions explicit.

-Wm