World: r3wp

Brian, are the parameters in R3 also unset in R3?

R3 has stack frames, so the entire frame - including the locals - 
is tossed after the function returns.

Closures are different though - a whole new context is created with 
each call, words and values both.

Closures are for doing "memory leaks" on purpose :)

Will we get any control over the stack?  So that we can potentially 
perform recursive operations without overflow?

Unlikely, since most tail recursion optimizations require an optimizer, 
or at least a compiler. Manual access to the stack is a security 
hole (unless the language is Cat). Accept that REBOL has real loops 
and that imperative programming is more efficient in an interpreted 
language :)

REBOL was designed to be interpreted efficiently. Don't compare it 
to languages that were designed to be compiled (like Haskell) or 
languages that aren't designed for efficiency (like Scheme).

Yeah I understand that.

REBOL 1 had tail-recursion optimizarion. REBOL 2 got rid of it on 
purpose, and got 30 times faster as a result :)

There were some other tricks that contributed, like getting rid of 
continuations and ELSE.

Carl sharing this much with you or how do you know this about REBOL?

I was one of the beta testers of REBOL 2 - I've been around that 
long :)

I can't remember what version I started with REBOL in.  I just know 
the year was 98.

But I walked a way a bit at times as the lack of development waned.

Earlier than me - I started in 99, with REBOL 1.0.3.

I remember back then we had Holger, Jeff, and Sterling.

I miss those guys. The beta list for R2 started a month after I arrived.

Yeah I found out about REBOL through a listserv I was on at the time 
with a bunch of Cisco Engineers.

I think I saw it mentioned on Usenet. We had Joel Neely too - he 
wrote the R1 interpreter, which was so slow (because it was like 
Scheme) that Carl had to rewrite it from scratch: REBOL 2. That is 
why Neely flames REBOL on the Scheme lists.

(I may have the name wrong though - I'm really bad at names.)

Wow, I remember that name but didn't know about the flames.

If I got the name wrong, sorry Joel :(

It looks like I *did* get the name wrong. Can't remember the right 
name either, but the flames went on as far as last year :(

Joe Marshal ?

Yeah, that might be it.

Yup, first hit on Google.

Joel Neely works for Fedex

and he too has moved on

Again, sorry Joel. He was fun too - lots of long, essay-like posts.

I think you are thinking of Joe Marshall who worked on an early REBOL, 
and has been critical of his continuations being removed from later 
versions.
http://ll1.ai.mit.edu/marshall.html

(Sorry -- did not see Anton's post  until after I send mine .... 
the old resync bug yet again :)

Joel still posts some interesting reading abut functional languages, 
but as Graham says, he seems to have moved on from REBOL:
http://joelneely.wordpress.com/

We had several good guys vanishing. Andrew Grosman, Adnrew Martin, 
Frank Sievertsen, Volker Nitsch, Romano Paulo Tenca - all skilled 
rebollers.

I am with REBOL since Carl left Viscorp, in 96. I do have early alphas 
- 0.9 something somewhere :-)

So, to continue my quest to understand ALSO, I'm now at:
1) It's useful to set locals to none in R2 (if done right).
2) It's used to close ports.
3) It's used to change directories back.

And 1) isn't an issue in R3.

4) It's used to avoid a temporary variable.

Geomol: I never said I do my-port: also... if you need to use a local 
word then you don't need also. I need also all the time.

time-it: func [label code /local s] [
        s: now/precise

        also do code debug/dprobe/label difference now/precise s label
]

to replace TAKE:  also last block remove back tail block

Good examples!

Gabriele, I wasn't very clear with my port example. I didn't mean 
a local word. I'll use your TAKE example. Let's say, we have this 
code:

take: func [block] [also last block remove back tail block]
...
item: take my-block


Have TAKE makes the code smaller, but is it more readable? You have 
to know exactly, what take does, but you have to with many words. 
And is it worth the overhead? Let's compare it to this code, that 
does the same:

item: last my-block
remove back tail my-block


The first version has the overhead of a function call and use of 
ALSO. The last version produce more code, if TAKE is used many times 
through the program. Let's look at a version of TAKE without use 
of ALSO:


take: [block /local item] [item: last block remove back tail block 
item]


This last version has a local word, item. To me, it seems like a 
tricky way to just save a local word. But maybe it's just me, that 
need to see this some more.

Have -> Having

BrianH wrote: "R3 has stack frames, so the entire frame - including 
the locals - is tossed after the function returns."


What is your opinion on this? Is it good or bad to make heavy use 
of the stack? I made some tests, but the picture isn't clear regarding 
performance. One test performed better in R3, another larger test 
performed better en R2.

Its superb idea.

Why?

Because their is limited room in the registers and the stack is the 
likely place for those operations.

How do you think, R2 works?

I assume it just used the registers and memory without the stack.

Just because Brian seems to be making a distinction.

Geomol, "just save a local word" - this is very useful !  I think 
ALSO just might take a bit of getting used to. It's like many other 
Rebol functions that we are now familiar with and use without thinking 
of its internal variable use. Do you think LOOP and REPEAT should 
not exist because they can be implemented with WHILE and a temporary 
variable? I reckon they are so cool to have in the language, because 
they make the code cleaner.