World: r3wp

SKIP with TRUE as its 2nd argument, which made me think it DID skip. 
SKIP with FALSE as its 2nd argument, which made me think it DIDN'T 
skip. With your PICK example, now I understand.

Yes, the initial imagined behaviour is turned around with logic. 
:) The PICK method is also faster than the EITHER method, if it's 
simple values to pick. If you have to reduce the block, the EITHER 
method is faster, as EITHER already reduce its blocks.

In R2, you can pick from functions, like:

>> pick :to-integer 1
== [value]

and it works with true too, but not with false:

>> pick :to-integer true 
== [value]
>> pick :to-integer false
** Script Error: Out of range or past end

In R3, you can't pick functions like this.

SKIP with LOGIC value seems reverse,  because it doesn't convert 
logic to integer before use it:
>> to-integer true
== 1

See Core group!

Yep, I saw it.

LENGTH? 'WORD is 4, LENGTH? /WORD is 5 ... not 4. Why? is the heading 
#"/" in refinement counted?

I guess it counts / as part of it:
>> to-string /WORD
== "/WORD"

>> to-string 'WORD
== "WORD"

But I don't know if it is a bug or not.

To be able to type a word of datatype word!, we need lit-word!. Else 
the word would be evaluated to it's value. So when you write
	length? 'word
, it's the same as
	length? first [word]
To get what you want:
	length? first ['word]
or
	length? quote 'word

It's kinda interesting, that you can take the length of words in 
R3. You can't do that in R2.

thats right, same for refinement also.

and above code gives different result in R2:
>> to-string 'word
== "word"
>> to-string /word
== "word"

both 4 chars lenght.

Funny!

These different words are all part of the typeset any-word!. In R3, 
you can see, what datatypes are part of a typeset with:
	? any-word!

It's interesting, issue! is also an any-word! in R3. It's not in 
R2. But issues have different syntactic rules than words:

>> #1a
== 1a
>> '1a
** Syntax Error: Invalid word-lit -- '1a

Correction:

>> #1a
== #1a

Same can be said with refinements:

>> /1a
== /1a

which looks to me like an error.

it is because of lit-words cannot start with a number but refinements 
and issues can.

Yes, but what benefit do you have from refinements starting with 
a number?

actually nothing :)

it is useless because you can create a function like below, but you 
cannot use it:

>> f: func [/1a] []
>> f/1a
** Syntax Error: Invalid integer -- 1a

IIRC it was discussed that numeral refinements should be removed 
from R3.

in the source code of load-module, the first line is ASSERT/TYPE 
[LOCAL NONE!]   ... Why?

Geomol, refinements are not just for translating to paths. You can 
use a subset of the possible refinements for that purpose, but rest 
can be used for whatever reason you like in other dialects. REBOL 
is not just the DO dialect, remember. (This is the official answer; 
I am just writing it out again, for the 4th time this year.)

Maxim, it was discussed and that proposal was rejected.

Jerry, the /local refinement is just another function option. If 
you provide that option when you call that function, you can provide 
initial values for the "local variables". In the case of sys/load-module, 
the security and control flow of that function depends on the local 
variables being initialized with the none value, so we want to avoid 
the /local option being used when the function is called. When a 
function refinement is not used its value is none, so if you want 
to ensure that it is none and trigger an error if it isn't, ASSERT/type 
[option none!] is the most efficient way to do this in R3.

After Carl asked me that question, Jerry, and got that answer, he 
wrote a blog where he suggested making /local special in functions. 
While most people are in favor of that (not half of the gurus), this 
proposed change to /local hasn't been done yet and we don't know 
if it will ever be done.

Thanks very very much, BrianH.

(This is the official answer; I am just writing it out again, for 
the 4th time this year.)

Why bother? No matter how many times you write it, this still is 
bad design. Or lack of design and bad implementation. It's like having 
integers, you can only use for the PICK function, but can't make 
arithmetic with.

After Carl asked me that question, Jerry, and got that answer, he 
wrote a blog where he suggested making /local special in functions. 
While most people are in favor of that (not half of the gurus)

 - then I must have a problem with reading comprehension. I rechecked 
 the discussion of this twice and came to a completely different conclusion

My numbers as seen from the discussion:

discussing: 11
for the change: 0
against the change: 2
neither for nor against the change: 9

I did not try to categorize the votes futher to guru/non-guru, btw

I'm looking at what kind of functions, R3 has:
>> ? any-function!

ANY-FUNCTION! is a typeset of value: make typeset! [native! action! 
rebcode! command! op! closure! function!]


And then I come to think, if it's a problem having both native!, 
action! and function!. Should all 3 be seen as function! ? Having 
them all and now with the addition of closure, what if a native act 
like a closure? Should it then be a native-closure! ? Same with action! 
.


And what if it's possible one day to make operators, should we then 
call the current operators for nop! (or native-op!)? I guess, these 
types originated, because they're dealt with differently internally, 
but should the users have to deal with the differences?

I think, that the answers to your questions are simple.


Closures and functions (while being nonnative) are so different, 
that it is more convenient to have them as different datatypes.

what if a native act like a closure?
 - can you name any native that does not?


As you mention, the current datatypes are likely the most convenient 
for the implementation.

I agree on distinguish between closures and functions, but maybe 
those whould be the only two, and then skip native and action. I 
remember being a bit confused about especially action! types, when 
I started on REBOL.

How can that "confuse" anybody? Something may confuse you only if 
it suggests something that proves wrong later, which is not the case 
of two datatypes being used instead of just one you seem to prefer.

It confused me, because they are called differently, so as a programmer, 
I think "ok, this is two different things, so I have to use time 
to learn the differences between e.g. functions and natives, or natives 
and actions, and how to use them correctly". And in fact, as a programmer 
I can very well ignore the differences, because the 3 types works 
exactly the same in my programs.

But the difference between functions and natives is obvious - speed

:)

I badly written native might be slower than a well written function.

You can certainly invent any number of generalizations, but you will 
not be able to find any example, I bet

I think, it was Bertrand Meyer, who wrote, that a datatype is recognized 
by the methods, you can use on it. In REBOL terms, what you can do 
with a datatype specify it. If you can do the same with a native! 
and a function!, they're the same datatype.

OK, then, how do you get the body of a native?

But, the fact is, that, seen from the Meyer's perspective, there 
should not be any distinction between actions and natives...

That is up to the implementor/designer to deside. :-) Maybe it should 
be a number, like actions returns in R2, or none as R3 do.

We can still try to get the body of a native and action, like we 
can with functions. So we can use them exactly the same way.

There is not "body of a native" you get. Both in R2 as well as in 
R3 you get just a "replacement value"

Correct! But that doesn't remove the fact, that I can use the method 
to get bodies on natives and actions, just like I can on functions. 
The methods define the datatype.

Aha, so you are saying, that it does not matter whether you get a 
#[none!] or a block?

I see it as a huge difference.

It is actually the same difference as a difference between causing 
an error or obtaining a block.

(a "caused error" can be considered a "special value" as well)

...and that is not my invention, you can find that principle in descriptions 
of many programming languages