World: r3wp

USE uses the body of the affected code *as* the body of the inner 
function, so it *is* a good example of this pattern, if you ignore 
the fact that USE in particular can be rewritten so it doesn't use 
an inner function.

But the claim is even wrong for this example.

Keep in mind that we use USE to illustrate because it is simple and 
shows a lot of the problems we are trying to solve in its existing 
code. USE is being used as a standin for the many other functions 
that would be affected by these issues. The fact that USE can be 
rewritten doesn't mean that the other functions can also be rewritten.

All you have to do is construct a correct inner function, instead 
of an erroneous one.

USE's inner function is not erroneous, not in the slightest bit. 
The whole point of it is to rebind the code block passed to USE.

Yes, then simply rebind it properly.

It does rebind properly.

Your example does not. It improperly rebinds a definitional return.

Instead of only the local vars.

You grabbed that phrase that I was answering from the section where 
binding with definitional return was the only way to bind. There 
is no option in that section (and that fact is listed in the advantages). 
In that section, definitional is the only way to bind.

Sure there is. BIND + DO.

That is rewriting to not use an inner function. Which that phrase 
was referring to cases where that is not possible.

If you are claiming that there are no such phrases, fine. But assuming 
that such cases were possible was the premise that led to the "you 
have no recourse".

no such phrases -> no such cases

Which is hypothetical as it is easy to show there are no such cases. 
So inner functions have nothing to do with it.

And even if you insist on that hypothesis, the claim is still wrong.

Sorry, inner functions are the easiest way to implement certain things. 
And we need to consider that too-complex functions or ones that use 
arcane workarounds are getting rejected for that reason alone nowadays. 
Most of the native changes in the last 3 releases of R3 have been 
to deal with situations like this. For these proposals, easy trumps 
possible.

So even the FOREACH workaround would be enough to prompt a change 
now. For that matter, the most recent module system rewrite was specifically 
for that reason. The new module system doesn't do anything that the 
pre-108 rewrite didn't do, but it is easier to use. Easy by default 
is the top priority.

The only reason definitional-only might be chosen is because it is 
easier to understand than the other models. That alone might trump 
the places where it still doesn't work. I hope not, because the "option 
to not rebind RETURN and EXIT" is really simple to specify and much 
easier to do than the workarounds that you have to do if you don't 
have that option, workarounds like your BIND + DO, especially when 
you consider 'self issues that prevent you from using objects for 
this kind of thing (hence the FOREACH).

So the real disadvantage in the "inner function" paragraph is that 
you can not write a function which does not rebind RETURN.

(Or at least that's the claim.)

Yes. I'm sorry for the confusing phrasing.

So assume that in this case "not possible" could in some cases mean 
"not possible to get accepted as a mezzanine because it's too Scheme-like" 
or "not possible for a regular programmer to come up with a workaround 
like this", because both limitations have real examples that have 
already manifest.

More precisely, the disadvantage is that we don't have an any-function! 
constructor which does not rebind RETURN in the function body.

And the claim is false because of the workaround with the direct 
function value references, which I came up with later. Only the words 
are rebound.

We actually need that option for both function! and closure! types, 
because of their different contexts. It is easier to add this as 
an option than as different types.

Especially since Carl is the one who suggested options in the first 
place, so we know it's possible to implement.

That's why I said any-function!.

not possible to get accepted as a mezzanine because...not possible 
for a regular programmer to come up with a workaround like this" 
- why, then, was my CLOSURE constructor accepted?

No, it would need two added function types, not just one. And names 
for those types, and names for the wrapper functions that create 
those types, and so on. An option is easier.

We are talking past each other.

That was a backport, Ladislav. R2 has more lax standards. We are 
trying to cut back on that in R3, but R2 is a lost cause.

The disadvantage is that we don't have a function constructor which 
does not rebind return in the function body.

If you want to talk about intimidating R2 functions, look at APPLY 
or MAP-EACH. Neither of those would be accepted for R3.

Agreed, Andreas. I was just saying that a spec option is a better 
solution to that problem than new datatypes.

Yeah, and as I did not suggest new datatypes, I was wondering where 
that came from.

we don't have an any-function! constructor...

Guess I misinterpreted that :(

Which was meant to imply that we have neither a constructor for closure! 
nor for function! nor for any other user-definable function type 
:)

Misleading, though. Sorry for that.

One of the goals of the native changes in R3 is to cut down on the 
need for arcane workarounds in regular REBOL code. For every arcane 
workaround that you might see in a mezzanine, you will see the same 
workaround need to be done over and over again in user code. Usually 
badly. There have been a host of native changes to make regular REBOL 
code easier to write and read and cleaner to look at. We even got 
more of these in the last 3 releases.

For that matter, that is what the call for idioms is for.

We can backport stuff from R3 to R2, but what we can't backport is 
simplicity :(

Btw, Ladislav, thanks again for the CLOSURE constructor. If you hadn't 
come up with that great a solution then R2 likely wouldn't have gotten 
closures at all, and none of the other fake datatypes would have 
made it in either, which would have been a real tragedy if we missed 
out on the typeset! stuff.

If I did not came with CLOSURE, not even R3 would have gotten it, 
I bet

True, but you notice that R3 got it as native. We are trying to hide 
complexity.

Strangely enough, when I backported CLOSURE to R2 I had forgotten 
that you had written a version, but what I came up with ended up 
being the same code, exactly. So I attribute it to you through my 
unconscious :)

As an additional advantage, the meaning and expected behavior of 
'''return''' and '''exit''' from code blocks is clear with dynamic 
return, since dynamic return is defined in relation to the flow of 
calls to functions rather than in terms of lexical scoping.

That is highly debatable.

Especially if already using lexical scoping terminology, there's 
nothing that makes dynamic scoping instrinsically more clear than 
lexical scoping. And even when limiting this discussion to REBOL, 
where lexical scope is only faked, that does not make the concept 
in any way less "clear" than it's non-faked dynamically scoped counterpart.

It is clear *once you accept the idea of dynamic scope*, which is 
an inherent part of the semantics of all dynamic escape functions. 
And that limitation is listed as a disadvantage in the same model.