World: r4wp

Thanks......I can see now how SKIP can work on an image bitmap
    img: to-image #{....plausible hex stream....}
    skip img 2x2


However, TAKE does not work on image bitmaps.....Are there other 
types of bitmap?

The bitset type could be thought of as a one-dimensional bitmap of 
depth 1, but that's stretching the defitnition a little :)

:)
Is TAKE intended one day to work on image bitmaps?
Or is there another use for:
     TAKE/DEEP word 10x10

No, because TAKE removes from the original, and that would change 
the dimensions of the original in the case on an image, assuming 
it's possible (you can't take a hole from the middle, for instance). 
So you mean COPY/part here.

My confusion is due to the help for TAKE saying the /DEEP arg can 
take a pair! -- So I was looking for a usage case.

Well, maybe it was intended to work on image (if so, sorry). I'd 
have to review the R2/Forward code to be sure, since its version 
of TAKE would have replicated that. It's a really weird thing to 
do to an image though.

The R2/Forward TAKE makes reference to an image in its code, but 
not in its typespec. Weird. A bug?

BrianH: If I wanted to take a subsection of an image, why wouldn't 
it create a new image with just that subsection, and then replace 
the "taken" part in the old image with 0.0.0?  Or am I understanding 
the purpose of 'take incorrectly?

First question about REBOL(£):

Is there an article which explains how REBOL3 loads words in memory 
and how their are organized, stored, evaluated ?

Here's a starting point for such an article.....
   http://www.rebol.com/docs/expert-intro.html

Bo, TAKE physically removes stuff, it doesn't leave a hole.

Has anyone worked with the Amazon aws services?  I'm not sure how 
to "Calculate an RFC 2104-compliant HMAC with the SHA256 hash algorithm" 
as described in step 8 on page 62 here:  http://awsdocs.s3.amazonaws.com/Associates/latest/prod-adv-api-dg.pdf

Just trying to look up prices based on SKU.  This is the string I 
have so far:


http://webservices.amazon.com/onca/xml?Service=AWSECommerceService&AWSAccessKeyId=[mykey]&Operation=ItemLookup&ItemId=041554286915&IdType=SKU&Timestamp=2013-03-19T10:04:31Z&Signature=[this-is-what-I-need]

Graham has, but hit github repo for it seems to be empty. Not sure 
where he has it posted now.

Thanks Gregg - I'll see what he knows :)

You can't yet because we can't calculate a sha256 .. we only have 
sha1

so, you'll have to use an external library to do that part

I'm looking into pitching a Rebol programming class to the community 
college here (I'd teach it).  I know of NickA's excellent tutorials. 
 What would you all suggest for a class text.

I found the 'Rebol for Dummies' book quite disappointing for my personal 
use, but it might be good as a course book though. It certainly covers 
a lot of ground quickly. I personally preferred Nick's video series 
http://re-bol.com/rebol.html.Somehow more interesting and easier 
to digest. Just my personal experience.

I also have 'Rebol. The Official Guide' which at 700+ pages is massive 
and way too much. Also, no graphics included, so I would not necessarily 
recommend that as an introductory course book.

Yes, I also have Rebol for Dummies, Rebol: The Official Guide, and 
just about every other Rebol book in print.

I'm currently leaning towards Nick's tutorials right now.

Is the class for new programmers or people new to programming?


If the latter, Olivier Auverlot's REBOL - A Programmer's Guide" might 
suffice.

Full disclosure - I translated the book from French to English.


The content of the book is a little dated by newer than Official 
and Dummies.

by -> but

After looking at 'Rebol for Dummies' again, that is what I'd recommend 
for a community college course. Even if a little dated.

Getting enough copies of the other books out there may be difficult.

@Graham - thank you, yes I'm aware we only have sha1.  It looks like 
OpenSSL, PolarSSL, MD5Deep, cryptlib, and a bunch of others are out 
there.  Have you used any successfully with AWS?

I wonder if the Saphirion guys have sha256 going.

The AWS functions I use have sha256 optional

Bo: There is Viktor Pavlu's "REBOL Essentials" in pdf form.

Here is the link: http://vpavlu.plain.at/REBOL/tutorial/

There is a beginner's level View/VID part too.

PeterWood, caelum and Endo: Thanks for the ideas.  I've seen Olivier's 
book, but I don't have a copy myself.  That might be a good choice.

The book by Viktor Pavlu looks promising.

I used that to get really more familiar with REBOL. It is a good 
introduction, unfortunately it is not finished. The up-to-date is 
less bothering for it is the basics that's covered and those are 
the same still.

Olivier's book is pretty good IIRC.

Hi all, I wrote

https://groups.google.com/forum/#!topic/Rebol/jL55YPQXWW4

to give an idea what are closures good for in R3.

Nobody will use functions anymore after that demonstration Ladislav!

:-D

I should check whether closures are implemented optimally, having 
the source code available.

Hmm, I thought that's what funct is for, but apparently I was wrong 
- funct just seems to make all set-words local, but not passed in 
arguments ...

well, this is something else than what FUNCT does. Making some variables 
local can be useful for closures as well.

Great works Ladislav, added to http://rebol.informe.com/wiki/view/Rebol_3-closure
 wiki

MaxV: one more improvement to the text; I wrote:

c: closure [a [number!]] [func [b [number!]] [a + b]]

, but, actually, I think that

c: closure [a [number!]] [closure [b [number!]] [a + b]]

wold look better (more uniform)

What I am still afraid of is the fact that the "Closure" name could 
scare beginners looking sufficiently "unfamiliar" and "exotic", while 
I think that what *should* scare beginners as far as the behaviour 
is observed is actually "Function".

When all these renaming issues are discussed I think that it might 
make sense to think about the name in this context as well.

I agree that the name "closure" is not user-friendly. Also, I wonder 
if it shouldn't be the default function constructor (also thinking 
loud for Red). I'm still unsure about that though.

Certainly the series copy trap is the one beginners will fall into 
most. Higher order functions won't be in their code, probably until 
they are comfortable with 'closure.

...but the GUI example should be in the repertoire of beginners, 
don't you think? (and it even "caught" Cyphre, so he asked me how 
to do it properly using function, so I had to tell him: "don't")

Agreed with both of you on naming. Now is the time to consider what 
to change in R3 and what to use in Red. 'Closure has meaning beyond 
Ladislav's current examples. Do we name things for new users and 
novices, or experts? For me, name things clearly, and supplement 
with docs if the names don't match expectation.