AltME groups: search

Maybe you can use Rebol and  try to implement a curriculum similar 
to HtDP.  

The Structure and Interpretation of the Computer Science Curriculum 
http://www.cs.brown.edu/~sk/Publications/Papers/Published/fffk-htdp-vs-sicp-journal/

My preconception is that adding the graphical layer complicates things 
too much 

 -- A valid concern in many environments, but VID is great, and simple, 
 for simple things.


view layout [button "Show help" [alert "Sorry, I can't help you"]]


No need to manage the event loop, no redraw handlers (until you need 
to get into them of course), just put an action block after a face 
style and it binds to it automatically.

Could not find a free tool that allowed al the features we wanted.

It needs Chat (writte), Talk (Spoken), Video, and several Whiteboards, 
and a way to view somoeone's computer screen.

Google Desktop has a plugin that makes GTalk able to make a chatroom, 
and another that allows you to share part of your screen with someone 
on your buddy list.  I don't know how well they work, thouhg

Project 1: Read a web page given a URL, find some data in the page, 
append it to a file on disk. Read the given disk file et show the 
data on screen.

Project 2: Establish a two way connection using tcp/ip and save the 
history on disk.

I'm looking for a LEARNING MAP that could be used as a fast track 
to learning to build interesting little applications.

Yeah, that is kinda in the progess of being built.  There are some 
awesome resources
but they need to be tracked down sometimes....

The cookbook  http://rebol.net/cookbookbeing one starting point.

rebol.org  has a lot of scripts, but it requires reading code a lot 
of the time....
The REBOL Viewtop  (desktop command at console)
    REBOL Folder ->Tools->Word Browser is not bad for options

I'm sure, as the pros keep saying, that once you have learned Rebol, 
it is very fast to code applications. The problem is that it might 
be that to get to that point takes quite a while

I can read the code. The thing is I have yet to get to a point where 
I can sit down and start thinking code to do things.

I'm looking for a set of basic essentials, of sort, that can be taught 
to a beginner so that he/she can start coding useful stuff in, say, 
3 to 5 hours.

Read those a couple of times. I teach C++. Know a dozen more languages, 
including Prolog.

To come to the point of teaching Rebol, I will have to find some 
structure in the language that permits me to extract the "basic essentials" 
in view to start students to code in a relatively short time.

yes, that is a problem as far as learning goes.

Like a Zen koan ;-)

Here's a nice tutorial.. http://musiclessonz.com/rebol.html

I hadn't seen this one. Based on View? I was assuming it to be simpler 
to stick with Rebol/core. Maybe not.  This one seems real good at 
a glance. Tks Brock. And tks btiffin for all the pointers.

view is core for all except gui. + some commands ending with -thru, 
'read-thru and such. they are the same as the short form, but use 
a cache.

Reichart: I'm surprised the tools you are wishing for in order to 
start holding online classes aren't already build in Rebol... From 
what I've seen, all the bits and pieces seem to be there already, 
maybe except for a whiteboard. No?

Rebol is a language...

To everyone:

What characterize a good learning book? Do you prefer thick books 
with deep explanation and many examples, or do you prefer the thin 
book with the essentials? Look at your collection of technical book; 
about computer languages, OSs, databases or what you have. Which 
ones do you like, and which ones is no-good?

I'm a newbie and wanted to ask this question on a simple rebol program. 
 If I have a variable COUNT and I wanted to write this value with 
a literal could I do this:  write OutFile [Count " Total lines"]/append. 
 But the word Count is not evaluated and I get "Count Total lines" 
instead of "8 Total lines".  What do I need to tell rebol to return 
the value of COUNT?

A suggestion: Many words in REBOL can do more than one thing, sometimes 
depending on data-type of the argument or the use of refinements. 
It's almost impossible to remember it all. So as a new one to the 
language, check the help for the new words, you're learning. Like
>> ? reduce
>> ? compose

As a newbie, what suggestions do you have for me to debug my rebol 
scripts.  For example, I have a script called "Convert_to_Table" 
that I am just starting to write.  I can execute it -stand alone- 
and see the results of the run, but what I would like to do is be 
able to see what the console has for any values.  In other words, 
when I double click the "Convert_to_Table" I can see the results 
but not ask the console questions like print Count or the like.  
How do you suggest a newbie debug a script?  Should I go into console 
first and then perform a "do Convert_to_Table" and then be able to 
ask questions of console, or is there another way?.

Yes, use the console! Also use PROBE in the script to check values. 
You can put PROBE in anywhere, also in the middle of a sequnce of 
words.

Hi Volker,  after a few variations, I used this: print reduce ["var-name= 
" var-name]  What is the syntax for '??

?? - it's same as with probe:

>> ?? probe
probe: func [

    {Prints a molded, unevaluated value and returns the same value.}
    value
][
    print mold :value :value
]

?? does a get, you can put it in expressions before variables

Volker: no, ?? changes the meaning of expression in case you put 
it before function:
>> f: func [a][a]
>> a: 1
== 1
>> b: probe f a
1
== 1
>> type? :b
== integer!
>> b: ?? f a
f: func [a][a]
== 1
>> type? :b
== function!

Wow, I guess there are a lot of ways to "explain" how rebol is evaluating 
an expression.  Thank you.  I will try them all sometime.

P.S.  In AltMe, what do you guys type to get a carriage return without 
sending the AltMe message until you do an <enter>

This is a test
This is a test
OK It works!

Ahhh so much to learn and not enough time!!!  Thanks for your patience
Ok, on to another issue.


I have a text file as a printable report that contains several pages 
within it.  Each line can be as large as 132 columns wide (or less).

- The literal  "    Page " will begin in column 115 and that indicates 
the start of a printed page.


I want to write a script that will read this text file one-page-at-a-time, 
so I can do some processing on the page.


How do I write a script to load in a single "page"?  I am guessing 
that I need to open a PORT and have rebol read all the lines until 
I get "....Page." in bype position 115.

Any suggestions?

you can use read/lines to have all lines in a block

I need to load in a single page at a time, then "process" that page 
before going on to the next page and processing it.


Are you suggesting that I go ahead and read in all the lines of the 
report and then go through that block to identify a page?

if parse/all[115   " "   "Page" to end] ["its a new page"]
(not testet)

if parse/all  LINE [ 115   " "   "Page" to end] ["its a new page"] 
;..

Hi everyone,


I want to write out a Ruler line to a text file for a specified length 
of bytes similar to the following for 125 bytes in length:

----+---10----+---20----+---30----+---40----+---50----+---60----+---70----+---80----+---90----+--100----+--110----+--120----+

I tried the following code, but not what I want:             Ruler:	for 
Count 10 125 10 [ prin "----+---" Count ]     I got this instead:

----+-------+-------+-------+-------+-------+-------+-------+-------+-------+-------+-------+---Ruler: 
120              Any suggestions?

My version produce a lot of copies of the string. Volker's suggestion 
is better, because it don't have these copies, so doesn't disturb 
the garbage collector too much.

Volker -- I'm a newbie so bear with me,  I don't understand your 
suggestion.  Do you mean I should do this:
Ruler: for Count 10 125 10 [ prin "----+-----"    then what?

You could also go for a combination with one little string, that 
you change (by putting in the number) and print.

This is a way without copies:
str: "----+-----"

for Count 10 125 10 [change skip str either Count < 100 [8][7] Count 
prin str]

prin will insert a space though, so you may want to do   print join 
"---" count   instead.

I guess, you have to convert it. I've once build a RebXML format, 
that could be transfered to/from XML. I can handle utf-8. You can 
find code to convert from utf-8 here: http://home.tiscali.dk/john.niclasen/rebxml/xml2rebxml.r
(search for unicode)

The other way can be found here: http://home.tiscali.dk/john.niclasen/rebxml/rebxml2xml.r
(search for iso2utf-8)

Thanks Geomol,  Since I am a newbie, I can easily resave the files 
as ANSI instead of UNICODE and avoid the conversion problem, at least 
in the short term.  Once I get my "Convert to Table" program working, 
then I can look at your links to convert from UNICODE.

When you try to save a document under Notebook, the encoding choices 
are UTF-8, UNICODE, ANSI among others.  UNICODE may be the same as 
UTF-16 because it does look like every single character is saved 
as two bytes.  


The code (rejoin extract read InFile 2) does eliminate the double 
characters but I noticed that the entire file is still double spaced 
-- as if the newline is coded twice and not removed from the rejoin. 
 But that extra newline may be an annoyance than anything else.

Hello my teachers.  Is there a more elegant way to create a ruler 
than this in rebol...

Str7:	Str8:	"" 

Ruler:	rejoin [	for Count  10  90  10 [ Str8: rejoin [ Str8 "....+..." 
Count ] ]

  for Count 100 250  10 [ Str7: rejoin [ Str7 "....+.."  Count ] ]
	] 
print Ruler

I don't know about more elegant, but here's a func, just for fun.

Patrick ... on your AS400 problem .... how is the data transferred 
to the PC?  Is it directly from an AS400 file via the data transfer 
utility built into, or is it a file from the IFS ?

(I have used Rebol to read data transferred from an AS400 and didnt 
get the data as unicode.)

Patrick, on the double newlines. Can you inspect the result of   
read InFile ? How many newlines are present at that point ?
Useful rebol words:
	NEWLINE	; this is the newline character that rebol uses
	CR	; carriage return character
	LF	; linefeed character
	CRLF	; both CR and LF in a string

I don't think EXTRACT is at fault, it does a very simple job, getting 
every second character.

Hi Anton -- This is my simulated input for a unicode text file:
	Line1...10....+...20....+...30....+...40....+...50
	Line2...10....+...20....+...30....+...40....+...50
If I run this code:
	InFile:		%"Small In unicode.txt"

 InText:	rejoin extract read InFile 2	; Convert from UNICODE to ANSI 
 but keeps double spacing.
	OutFile:	%"Test Out.txt"
	write OutFile InText
	print InText	
I get these results
	ÿLine1...10....+...20....+...30....+...40....+...50
	
	Line2...10....+...20....+...30....+...40....+...50
	

I get them in the output file when I use the Rebol editor, and in 
notebook (when I open the file) and I get them in console when PRINT 
InText.

At first, I thought it just be some stray bytes comming from the 
AS400, but I was able to re-create a file using Notebook and get 
same results.
Any of you should be able to test this out by:
1.  Open Notebook
2.  Type in some text
3.  Save the file with Encoding to UNICODE

Ok -- I think I have it:   my sample input is a two line text field 
in UNICODE like
Line1
Line2

as-binary InText shows #{FFFE4C0069006E00650031000A000A004C0069006E0065003200}

FFFE is a "byte order mark" -- something that has been slipped in 
at the beginning of the file to indicate the file is in UTF-16, little 
endian format....If it started FEFF you'd have to extract all the 
other bytes. 

Looks like the original file (or whatever did the EBCDIC to UTF-16 
conversion on the AS400)  is using A0A0 to mean newline. You may 
need to clean those up by hand:

Question to all:   

If I have a block of data inside of In-text like this:
	Line A
	Line B
	Line C

How can I print the line number (position in the block) along with 
the contents of the line?               I tried this but it didn't 
work:
foreach Line In-text [ print rejoin	[ Count:	Count + 1	]	Line ]

Now that I think of it, I probably do not need to manuipulate a Count 
variable  -- I can probably use INDEX right?

I tried this out but not getting the results I wanted:

	Data:	head In-text
	while	[not tail? Data] [
			print	[index? Data Data ]
			Data:	next Data		]

I'm getting this:
	1 Line A Line B Line C
	2 Line B Line C
	3 Line C
Any suggestions?

Give me enough time, and I will figure it out --- :-)

Data:	head In-text
while	[not tail? Data] [
		print	[index? Data first Data ]
		Data:	next Data		]

Is there a better way to code this kind of thing?

One way:
data: [a b c]
for n 1 length? data 1 [print [n data/:n]]

Situation:	I want to read in an input file and parse it for some 
strings

Current:	My test code will do the parsing correctly IF the input 
block contains each line as a string

Problem:	When I try to run my code against the test file, It treats 
the contents of the file as a single string.

Question:	How do I have Rebol read in a file as one string per line 
instead of one string?
In-text:	[	"Line 1                        Page     1"
		"Line 2    Name      String-2"          
		"Line 4    Member    String-3 on 12/23/03"
		"Line 5    SEQNBR    abcdef               "                
		"Line 6       600    Desc 1 text         12/23/03"
		"Line 7      5400    Desc 2    Page 4    12/23/03"
		"Line 8    Number of records searched	]
 Get-page:		[thru "     Page "	copy Page-id to end]
 Get-file:		[thru "Name  "		copy Name-id to end]
 Get-member:	[thru "Member  "	copy Member-id to end]

 Page-id:	Name-id:	Member-id:	"-"

 for N 1 length? In-text 1 [
	parse In-text/:N	Get-page
	parse In-text/:N	Get-file
	parse In-text/:N	Get-member
	] 
 print	[ "Page"	Page-id		]
 print	[ "Name"	Name-id		]
 print	[ "Member"	Member-id	]

Thank you Sunanda -- That did work, but I thought Read/Lines would 
return a single line  -- no maybe that is Read/Line without the s 
 -- is that right?

Maybe not a problem, but overhead?

>> mulr: rebcode [a][mul a 2 return a]
>> mull: rebcode [a][loop 10000000 [apply a mulr [a]] return a]

From my tests calling a REBCODE function (or subroutine) using APPLY 
is by 100% slower than reusing the same code.

It looks like APPLY inside a LOOP is causing those problems.

time: func [b /local start] [
	start: now/precise
	do b
	print ["Time:" difference now/precise start]
]

rgba-to-int: rebcode [r g b a][
	lsl a 24
	lsl r 16
	lsl g 8
	or a r
	or a g
	or a b
	return a
]


draw-pix: rebcode [r g b a][
	apply a rgba-to-int [r g b a]
	return a
]

draw-pix2: rebcode [r g b a][
	loop 1000000 [
		apply a rgba-to-int [r g b a]
	]
	return a
]

probe stats
recycle
time [loop 1000000 [draw-pix 255 255 255 255]]
probe stats
recycle
time [loop 1000000 [rgba-to-int 255 255 255 255]]
probe stats
recycle
time [draw-pix2 255 255 255 255]
probe stats

A note about speed:
I've made an exponont function like this:

exponent: rebcode [b [decimal!] x [decimal!]] [
	eqd x 0.0
	braf 2
	return 1.0
	log-e b
	muld b x
	exp b
	return b
]

It can then be used in a rebcode function, e.g.:
apply result exponent [2.0 4.0]

An alternative way is to make a normal REBOL function:
exponent: func [b x][b ** x]
which can be used the same way:
apply result exponent [2.0 4.0]


It turns out, that using a normal REBOL function is faster in this 
example. It then occured to me, that it could be even faster, if 
APPLY was changed to support operators. Like this:
apply result ** [2.0 4.0]

Is that a good request?

it's faster than using a REBOL function. It works with POWER as it 
should with the operator **, so I'm happy. (I just noticed, POWER 
wasn't an operator. Didn't know that.)

Kru: this really seems to be APPLY related, because the following 
code crashes too:

mulr: rebcode [][return 4]
mull: rebcode [][loop 10000000 [apply a mulr []] return a]
mull

guys, how well does parse play with rebcode? It was said that parse 
is VM in itself, it is very right, but now we have some discussion 
about zlib support. Let's suppose we have rebol version on rebol.org 
and that we would like to speed it up. We can simple extend the idea 
to any other datatype (= in amiga terms, simply a file format, or 
protocol one). you will surely want to use parse. The question is, 
if you can speed up some things using rebcode?

Using APPLY with POWER may be a special case, because the equivalent 
is 10-11 lines of rebcode. So in this case, calling POWER with APPLY 
is actually faster than programming the POWER function inline in 
rebcode. (I hope, I make sense.)

bezier: rebcode [
	t	[decimal!]
	P	[block!]
	/local result m n n! i a b c d idx
][
	do result [copy [0.0 0.0]]
	length? n P
	div n 2
	set m n
	sub n 1
	;apply n! factorial [n]
	set n! 1
	repeat x n [
		mul n! x
	]
	repeatz i m [
		to-dec a n!
		;apply b factorial [i]
		set b 1
		repeat x i [
			mul b x
		]
		to-dec b b
		divd a b
		set b n
		sub b i
		;apply c factorial [b]
		set c 1
		repeat x b [
			mul c x
		]
		to-dec c c
		divd a c

		eq i 0
		braf i-not-0
		set d 1.0
		bra muld-d-a
		label i-not-0
		to-dec c i
		set d t
		;apply d power [t c]
		log-e d
		muld d c
		exp d

		label muld-d-a
		muld d a
		set a 1.0
		subd a t

		eq b 0
		braf b-not-0
		set a 1.0
		bra muld-a-c
		label b-not-0
		to-dec b b
		;apply a power [a b]
		log-e a
		muld a b
		exp a

		label muld-a-c
		muld a d

		set idx i
		mul idx 2
		pickz b P idx
		muld b a
		pick c result 1
		addd b c
		poke result 1 b

		add idx 1
		pickz b P idx
		muld b a
		pick c result 2
		addd b c
		poke result 2 b
	]
	return result
]

Pekr, with this histogram function:
histogram: rebcode [rgb result /local r n a b c] [
	length? n rgb
	div n 3
	repeatz i n [
		set a i
		mul a 3
		pickz b rgb a
		add a 1
		pickz c rgb a
		add b c
		add a 1
		pickz c rgb a
		add b c
		div b 3
		pickz c result b
		add c 1
		pokez result b c
	]
	return result
]

it takes 0.094 seconds on my machine to get histogram of 640x480 
pixel image.

The histogram, I posted, count combined rgb values (or light value 
if you like). To count rgb values individually, a little change is 
needed.

Right. I once talked with an astronomer working in Lund, Sweden. 
He told me about the software, they use. It's mostly based in code 
written in the 70'ies (in FORTH, if I remember correctly). It's good, 
well-tested software of course, but the user interfaces are terrible, 
often just a command-line. It could be interesting doing modern versions 
of some of that software using REBOL. But the scientists have to 
be 100% sure, the output is correct and the same as they get from 
the software, they use now. If the right function libraries were 
developed in REBOL (rebcode), I think scientists could be a good 
user-base (developer-base) for the REBOL language.

Geomol, they are probably using a domain specific language to drive 
their telescopes ... something forth pioneered.

Yeah, I would leave the scientists alone ... it's like trying to 
wean a unix user from their command line tools!

even big SBIG used parallel port back in the time we used ethernet. 
The sad thing is - no money, no music ... 4 ppl working part-time 
can't beat 80 full-time workers. But we did, for ourselves - I have 
our camera in my table ;-) And we build quite a few telescopes - 
REBOL is COOL for astronomy - dialects etc. wow ... the thing is, 
if it would be adopted ....

pekr, did i understand that u were using rebol 4 astronomy? could 
show me/us some of ur worx? a collegue of mine - whom i really want 
to b converted from php to rebol - is an amateur astronomist and 
such a stuff can give him the final pulse to start learning&using 
rebol

Speaking as someone who generates as well as wwrites rebcode, I would 
say yes. This frees up the non-typed opcodes to be rewritten with 
their typed equivalents by a type inferencer.

Yes, but a typecheck and a branch and a conversin even more.

(no chance some of you change a bit his color : you look the same 
all three)

Volker, the typecheck can be done by the programmer, or a type inferencer, 
either way statically. When rebcode gets a JIT those typechecks get 
put right back to implement generic math, because the real machine 
won't have it.

if i want a generic sum, people feed [ 1 2.5 3 ], it would be faster 
in rebcode, so makes sense. with hand-typecheck it would be slower. 
I guess its to rare to worry about, but i would keep the option.

but main reason is, its easier to remember, set seti setd add addi 
addd would be first thoughts.

We managed to give you a different color than us. :)

I get generic add by doing this:
    to-dec a
    to-dec b
    addd a b

You can skip one or both conversions if you can trace the type flow 
and be sure of the data types of the arguments.

Sorry, to-dec a a ...

3) come from asm68k that looks like that.

And rebcode, as a byte-code, is near ASM (even if more powerfull, 
ie: block!)

dot looks like a space and spaces are veryimportant in rebol-layout. 
i would not use that.

A period looks like a space?

in rebol most signs fill the space  if .. [ ..], not  if .. { .. 
}. a-word, not a_word. i like that

sure, but i can change the other way. why start with a bad opcode 
and replace it with a bad, when i can have it the other way around?

DideC: Add a choice.
4) INTEGER add-i mul-i div-i ... / DECIMAL add-d mul-d div-d ...

REPLY TO URGENT NOTICE:  i propose i.add, i.mult, i.div etc... this 
way we include to rebcode a some object like stuctrure but only applayable 
on fonctions /operation names 

this allow us to not mistake betwin rebol/core  funtions and rebcode 
ones. As type take a  !  in rebol syntax we can use i!add i!mult 
i!div i!sub etc... I think this syntaxe would be really attractive 
for coders abit to object language. I.add or i!add is directly understable 
i -> interger add -> the operation applyed to integer! args ...

rebcode uses a full value for an opcode, 16 bytes? not something 
comprimized? if so, that works badly with cache-prefetch. But i agree 
the opcodes should have word-based names. so 2 if we think we stay 
with int/decimal, 1-2 others, 4 if we think we get special code for 
more types than the alphabet has letters.

I prefer 1, as it is now. Keep it short. I think of the decimal variations 
like the normal ones, but with some extra (decimal has better precision 
and gives you decimals, so it's something extra than integer). It 
also take up more bits -> more bits, longer name. That's the way, 
I think. Also reminds me of C, where 10 is a short integer, and 10L 
is a long integer. (Not the same, but kind of the same thoughts.)

i clash with seti and such. then we should make everything integer, 
and have a setv for any-value.

I never liked that integers were treated like a default value in 
C. This leads to its typing problems, excessive casting, character 
as integer, ...