World: r3wp

I'll try to get in touch with Carl over this.

This one is a poll question everyone should not have trouble to answer. 
In R2, the USE function initialized the local values to #[unset!] 
for better user protection. In R3 (implementation quirk) the local 
USE variables are initialized to #[none!]. Which alternative do you 
prefer?

I, personally, do not mind much, but, depending on the result of 
this poll, I intend to adjust my policy when judging other cases, 
e.g. new functions, that are not yet implemented.

I think it should be the same, as if you were to use those values 
local to a function. Aren't they set to #[none] there too?

I sometimes have a tendency to write code like:

use [blah] [...body...]

and later move that code to:

func [/local blah] [...body...]

and it would be nice not to have to change the body.

Aha, OK, so 1 for the current R3 implementation.

thanks

+1 hanrik

(henrik)

USE3:USE2 = 2:0

But I have no problems with #[unset!] as well. But as Henrik says, 
better to be consistent with the function initialization.

As long as they use the same start value, I'm OK with either #[unset!] 
or #[none].

they use the same start value

 - so, I understand it, that what you actually want is the consistency 
 between "initialization of function locals" and "initialization of 
 USE locals"

(not minding much what value it actually is)

yes. the end-goal would be to not need to change the body.

thanks, leaving the score as is, but making a note for myself

Good argument, Henrik.

Ladislav, you wrote "the USE function initialized the local values 
to #[unset!] for better user protection."

Better protection than what? Or what is the protection? (Or do you 
just mean USE creating locals is the protection?)

Sorry, improving the formulation:


In R2, the USE function initialized the local values to #[unset!] 
for better user protection against uninitialized variables (variables 
not initialized by the user).

At least I have been told, that was the main reason for the existence 
of the #[unset!] value

Which means, that a variable being intitialized to #[unset!] behaves 
like being "uninitialized"

I hope it is clear now

Aha, that makes sense.

I have a slight preference for unset!, but the consistency argument 
overpowers it.

Which means, if I understood you well, that your favourite behaviour 
is:

    use [a] [type? get/any 'a] ; == unset!

as well as

    do has [a] [type? get/any 'a] ; == unset!

, the current behaviour

    use [a] [type? get/any 'a] ; == none!

and

    do has [a] [type? get/any 'a] ; == none!

being the second best only?

and

type?

(sorry for the cut'n paste mess at the end)

... Yes... but, if on a scale of 0 to 100, where 0 is unset! is my 
exclusive favourite and 100 is none! is my exclusive favourite, then 
my preference is about 49, with an uncertainty of ±10.
So I don't think my vote should count for much. :)

+1 for consistency between /local and USE. Do not care much if the 
initialisation value used is none! or unset!.

So, assuming that it is "impossible to change the FUNC variable initialization 
convention", I count: USE3:USE2 = 4:0

Please don't make REBOL into Haskell ;-)

Am I to understand, that some of the USE3/USE2 variants would do 
that?

Or, did you mean another property?

+1 for R3's USE. Uninitialized variables aren't really as much of 
a problem when:
- They are declared right there where you can see them.

- They are initialized to a known value that you can rely on or test 
for.

And if we are really concerned with initializing the values, we can 
just use LET, even if we have to add it ourselves.

Oh, and -1 for "change the FUNC variable initialization convention". 
The same arguments apply to function variables.

USE3:USE2 = 5:0

Is this simply a variant of known existing issues; and, if so, is 
it what R3 intends?

    if all [return none][print "I was printed"]
        R3: ==I was printed
        R2: == ** Throw Error: Return or exit not in function

Ditto with BREAK, EXIT

Crap, that affects IF too? I'll write up a ticket.

Wait, no, that is just #1509.

Nope, right the first time.

Darn, I had to look at the types-of to be sure. It's #1509.

Thanks, Brian, That was quick -- you know your error codes!

Only the top dozen most important ones.

Ah, there will _always_ be a top 12.

Am I to understand, that some of the USE3/USE2 variants would do 
that?

Just a joke, because the talk here is awfully mathematic, while REBOL 
is based more on English

The words of REBOL are based on English. The semantics are based 
on math (though not always arithmetic).

Ah, so I was right that you would like REBOL to become Haskell

Haskell is based on some of the same math, but mostly different math. 
More lambda calculus, less (I don't remember the name for the math 
of languages with state modification).

Brian: "And if we are really concerned with initializing the values" 
- actually, I am not. I am more like one of those wanting to have 
it the same way in functions as well as in other locals. (like Henrik, 
Oldes, Anton, Andreas). That is currently the same in USE, which 
I do not object against. This way, only object (and module) fields 
are currently initialized to #[unset!], although in the newly proposed 
LET we can choose. BTW, it looks to me, that it is good, that LET 
can accept any-word!, i.e. be more flexible than USE.

On the other hand, I am not sure, whether it is a good idea to allow 
empty VARS block in LET - that looks like a user error to me.