World: r3wp

Why I hesitated to write my preferences regarding indirect evaluation 
of lit-words was, that I felt the #1434 ticket was more about the 
explicit evaluation

The #1434 ticket is about making lit-word and lit-path consistent 
with each other, and about documenting some of the intentional changes 
from R2.

Are you OK with this, Ladislav?
>> 'a/1 
== a/1 
>> b: quote 'a/1  b 
== 'a/1 
>> do quote 'a/1 
== 'a/1

Or do you require this?
>> do quote 'a/1 
== a/1

Yes, but the summary says "DO evaluation...", which, for me, means 
either "inline evaluation", or "explicit evaluation".

All of this evaluation is done with DO. The question is *how* it 
is done with DO.

OK, nevermind. I prefer

    do quote 'a/1

to yield

    == a/1

to be honest

As long as that is documented, I would be OK with that too. Geomol? 
Maxim?

, i.e. I see a greater difference between direct and indirect evaluation, 
than between inline and explicit evaluation.

Then you can put your preferred behavior model (with that i.e. justification) 
in your comment, and we can get a consensus there through people 
agreeing with you. This would be the code:

>> 'a
== a
>> b: quote 'a  b
== 'a 
>> do quote 'a
== a
>> 'a/1
== a/1 
>> b: quote 'a/1  b
== 'a/1 
>> do quote 'a/1
== a/1

I will write it, removing the older (and maybe misleading) comments

Cool (because I definitely misunderstood that last comment).

one more question (I guess, that a kind of glossary may be of use). 
How about replacing the "explicit evaluation" by "immediate evaluation" 
to contrast it more with the "inline evaluation"?

may not be ideal, just wondering whether we could find something 
which would be obvious to be opposite of "inline"

I meant explicitly calling DO. The other two styles of evaluation 
are usually the result of calling DO implicitly (through function 
evaluation, IF, etc.).

All of those forns of evaluation are done by calling DO in one way 
or another.

OK, nevermind, I shall use "explicit evaluation" for now

We need to make sure that we don't follow the same pattern for set-words 
and set-paths. Explicit DO of set-word/set-path values doing any 
setting is another security hole.

I do not have any preferences regarding explicit evaluation of set-words 
yet (do not use it), but would be curious, whether there are other 
users having some preferences in that regard.

I like the current behavior of set-words:
>> a: 1 do quote a: 2 a
** Script error: invalid argument: a:
But the behavior of set-paths leaves a bit to be desired:
>> a: [1] do quote a/1: 2 a
== [1]  ; no error triggered, just a noop.

yeah an error there would be better.

Considering that the main use of that would be to get access to values 
in function code blocks that you shouldn't have access to, triggering 
an error seems best.

I'll write up a bug ticket about that.

I would like to direct your attention to the

http://issue.cc/r3/1641

ticket, since it is (IMO) directly related to the glossary.

I figured out a new way to express the equivalence that can safely 
be used for word! (http://issue.cc/r3/1882), path! (http://issue.cc/r3/1881), 
lit-word! and lit-path! (http://issue.cc/r3/1434), set-word! and 
set-path! (http://issue.cc/r3/1883), and get-word! and get-path! 
(current behavior), that matches the behavior of paren!. This code 
should work in all cases.

use [a b] [
    a: func [] ["blah"]

    foreach t compose [(paren!) (to-block any-word!) (to-block any-path!)] 
    [

        assert [any [all [error? try reduce [to t 'a] error? try [do to t 
        'a]] same? do reduce [to t 'a] do to t 'a]]
        assert [b: to t 'a strict-equal? to t 'a b]
    ]
]


Basically, the equivalence of an individual type would be this (using 
word! as an example):
    same? do [a] do 'a
    b: 'a same? 'a b


The important part of the equivalence would be that DO value would 
be equivalent to DO reduce [:value], that it be equivalent to evaluating 
that value inline *in a block all by itself*. That would deal with 
the parameter problem, with making sure that set-words and set-paths 
trigger errors properly, it even would work with refinements and 
issues.

The only thing that it isn't equivalent for is unset words of the 
word! type or as the first element of a path! - inline evaluation 
triggers an error, explicit DO just returns unset.

I mean, wouldn't be equivalent after those tickets go through. Do 
we need another ticket or are we OK with the unset word difference?

Didn't you forget about the difference between inline evaluation 
of blocks versus explicit evaluation of blocks?

No, I just didn't include them in that list. It's a special case.

yes, that exception should be kept, certainly

How about the unset word exception? Should explicit DO trigger an 
error too?

no harm if it does, IMO

That would also extend to unbound words. The harm would be in having 
explicit DO trigger an error in an otherwise harmless case that would 
be common in data. Do we need this error?

Consistency might be a good enough excuse to do so, but I don't want 
to break code unnecessarily.

(I am totally in favor of breaking code necessarily.)

For me, there is no trouble in it, but others should tell what their 
preferences are. (maybe they just don't mind much, I could tell almost 
the same about myself)

The advantage would be to trigger errors when you DO code that isn't 
properly bound or set. It's either an error that it isn't bound or 
set, or it's an error that you are trying to DO it.

Brian wrote:

<quote>
>> b: quote 'a/1 
== 'a/1 
>> b 

== 'a/1 ; regular evaluation of lit-path value does not convert to 
path 
>> do :b 

== 'a/1 ; explicit evaluation of lit-path value does not convert 
to path


So it's not exactly like parens, but it's what Maxim, Geomol and 
I would prefer.
</quote>

No, I just posted the observed behaviour. I don't agree with it.

I would expect this behaviour:

>> do quote 'a/1
== a/1

Or better, as I'm not sure, I like get-words as function arguments 
(see source of quote):

>> do first ['a/1]
== a/1

as I'm not sure, I like get-words as function arguments

 - this formulation is unfortunate. What the spec block of the QUOTE 
 function does is that it specifies how the argument expression is 
 handled. In R3 it means "don't evaluate the argument".

Yeah, of course get-words can be function arguments. :-)

As you said, get-words in function spec blocks. I'm also not too 
fond of lit-words in spec blocks. I know, functions like HELP and 
SOURCE works like they do because of this, but if used frequently, 
code will be less readable, as I see it.

The QUOTE function is fine, and it is actually necessary, since e.g. 
there is no LIT-LIT-WORD argument, so, to obtain a lit-word, the 
most natural way is to use

    quote 'a

If it's necessary, then we need to come up with examples of functions, 
that take a lit-word as an argument. I can't think of any.

Beside trivialities like TYPE? :)

that take a lit-word as an argument
- that looks unrelated

do we understand each other?

For example, the INSERT function can take a lit-word as an argument, 
if that is what you asked

...but why did you ask that?

Yes, that's an example. I'm ok with writing

insert blk to lit-word! 'a


I asked, because you said, QUOTE is necessary. I don't see it as 
really necessary.

(old discussion, I know) :)