World: r3wp

hmm, not sure ....

I understood it as follows - R3 will be componentised, RT keeps language 
(merely a dll), the rest is nearly open ... now the question is, 
how much is "the rest" :-)

I think that there was talk about console, some parts of View, so 
not sure ...

maybe the easier porting will be because there will be nothing like 
mysql driver inside etc.

but - those are just my speculations ...

http://www.rebol.net/article/0284.html

hehe, I noticed original R3 announcement doc was updated too on August-7. 
Now we at least know, what "Long Term" means - the document states 
Carl would like to see alpha available sometimes in the Fall 2006.....

when's that in months?

October?

difficult to say ... I just wonder, as for alpha, how it happened 
that first educated guess of author was half a year off? :-)

anyway - let's say it will be 2006 .... 2007 is gonna be the year 
of R3, and IIRC 10nth anniversary of Rebol. Devcon 2007 is going 
to be great I think :-)

What do you think about this test?

	; local variable stability
	[
		repeat i 2 [i: 1]
	]

it is interesting, that FOR is able to pass this test:

>> for i 1 2 1 [i: 1]
== 1

Now the question is, what behaviour we prefer

the repeat version, as this is what I would expect and call intuitive 
... the word 'i gets bound to the block and is always being reset 
- so an infinite loop 


so 'for seams to not care or at least keeps the state of 'i for it's 
own purposes - how should a user know this, even though some assignment 
like this might flag in most cases a programming error (and in the 
other case in a for loop one can't manipulate the state of 'i explicitely)

I would definitely prefer that 'i is bound to the block. You might 
want to do adjustments to 'i during the loop, although I don't really 
use that, but sometimes it can be useful with variable stepping or 
resetting.

Yes I prefer repeat too, (my initial thought, at least).
Were the bugs/issues with FOR ever fixed ? I can't remember now.

I also vote for the REPEAT behaviour.

Were the bugs/issues with FOR ever fixed ?
 - no

and will there be? :-)

maybe ;-)

well, surely, such thing is not main priority in such big task as 
R3 is :-)

Silly idea: how to use 'protect for the loop-var? is that to expensive?

I would like to know the difference between action! and native!. 
Thanks!

In Carl's REBOL 3 Blog Article #0039, he says that the ordinal functions 
(first, second, ...) are of the action! type in REBOL 2, and will 
be of native! type in REBOL 3.

actions are like "methods" (if you are familiar with OOP languages) 
for values.

i.e. insert series value is like  series.insert(value) in oop languages.

and series.insert(value) will not be true in the native instead of 
action type?

a native is more like a C function, an action is more like a C++ 
method. anyway it's mostly an implementation detail.

the distinction will make more sense once we get custom types.

so no speed differences?

what do you think about this:

    repeat i 3 [probe i i: "a"]

ladislav, I think that's OK. interestingly, you can skip with decimal! 
values to make a smaller step than 1. I noticed two funny things 
though:

>> repeat i 3 [probe i i: i - 0.5]
1
0.5
1.11022302462516E-16
-0.5
-1.0
-1.5
-2.0
-2.5


One is that 0 isn't exactly zero and the other thing is that it counts 
to the absolute value of 'i

funny, indeed

actually the "0 isn't exactly zero" says something else - there is 
an error in the computation, which is expectable e.g. for 0.3 - 0.1 
- 0.1 - 0.1 (binary floating point numbers cannot represent 0.1 exactly), 
but is not expectable for 1 - 0.5 - 0.5 , because such numbers are 
exactly representable using binary floating point

Humm. I don't like it. It violates  the contract for REPEAT.

USAGE:
   
	 REPEAT 'word value body

 

DESCRIPTION:
     
	Evaluates a block a number of times or over a series.
	REPEAT is a native value

.

ARGUMENTS:
	word -- Word to set each time (Type: word)
     

 value -- Maximum number or series to traverse (Type: integer series)
 
  ;;;;; This part of the contract is being broken by the example. 
  
	body -- Block to evaluate each time (Type: block)

In my opinion Rebol should prevent the programmer  from shooting 
himself in the foot.  Also there are other forms such as FOR and 
WHILE that can be used for loops with variable steps. Maybe CFOR 
should be added to the core language.  


The problem with [ repeat i 3 [probe i i: i - 0.5]] is that it obscures 
the intention of the programmer. Does he wants to iterate 3 times, 
or more? This is not clear with such code.

yes, Jaime, the example may be named "how to shoot yourself in the 
foot using REPEAT"

Henrik: well, actions need to look into a function table, but natives 
probably need to check the type. unless the code for the action/native 
is very small the speed difference is probably unnoticeable.

this is "a bit problematic":

all [true ()]
all [() true]

any thoughts?

actually, it *is* consistent, it only does not cooperate well with 
IF

>> true = all [true ()]
** Script Error: Operator is missing an argument
** 
Near: true = all [true ()]
>> true = all [() true]
== true

>> true = all [true ()]

** Script Error: Operator is missing an argument

** Near: true = all [true ()]

>> true = all [() true]

== true

Hmm. Why the breaking of symmetry?

IMHO the behaviors should be consistent.

It also seems that in the first case "all [true () ]" is not escaped 
after the first valid predicate and the parens are still evaluated 
which sort of explaings the error because unset! is returned. Maybe 
we need too allow do [()] should return none instead of unset!.

After some thoughts the breaking of symmetry is valid in this case. 
Still the error thrown due to the return unset! value is missleading.

Maybe unset! should be expelled from the  ALL and ANY natives. After 
all there is not much that you can do with unset!, but expelling 
it is going to be hard. Lad, I am curious about your opinion.

I think I'm happy with ALL and ANY as is.

Of that repeat example:   repeat i 3 [probe i i: "a"]

I think that repeat must be checking the datatype and breaking when 
it is wrong (ie. false = integer? "a"). This can be seen as protecting 
the user from infinite loops caused by such user mistakes. Jaime 
is right that this behaviour has not been written into the function 
description, though.

repeat i 3 [?? i i: 3.0]   ; different datatype, decimal instead 
of integer