World: r3wp

So in R3, zero is true and other than zero is false? I remember something 
about this. Why was it made this way?

Because 0 being false only makes sense for languages without a boolean 
type (logic! in REBOL).

I think TRUE? provides equivalent evaluation to TRUE or FALSE in 
the case for IF and EITHER. Often you won't need to convert some 
type to logic! in order to evaluate it with IF or EITHER, but TRUE? 
allows you to display what IF and EITHER would evaluate to and it's 
necessary for PICK. I did not know it was different from make logic!, 
but to me it this difference just makes TRUE? more valid and important 
in general.

So essentially true? only reports false when it meets a an actual 
false.

Also with NONE, which is where I find it to be important.

correct

which makes it slightly different from FOUND?

Henrik: "BrianH, what exactly does the :value do in function header? 
What is passed?"


What is passed in R3 is the argument, completely unevaluated. So 
you can write this:
    set quote a get/any quote b
instead of this:
    a: :b

What does this give in R3?

>> true? 1

Geomol, true.

John, any value passed that is not none or false will give true in 
R3 the way I understand it.

Ah, then I was wrong in my assumption above.

It's a departure from C way.  If you want the C way then use make 
logic!

makes sense now ... I think. ;-)

>> source true?
true?: make function! [[
    {Returns true! if an expression can be used as true.}
    val

][
not not :val
]
]

Sorry for crappy formatting.

I agree with Brian, I think it is more aligned with how REBOL operates 
with logic.

Paul, in R2 and R1 as well. The code is exactly the same.

Yeah, I agree Brian.

Geomol, you should get the same results for:

either :val [true][false]

Or pick [#[false] #[true]] not :val.

BrianH, perhaps it's time for a little cookbook recipe on MAKE. :-)

by the way,  make logic! also works with TRY

The full source of TRUE? is this:
true?: func [
    "Returns true if an expression can be used as true."
    val ; Note: No [any-type!] - we want unset! to fail.
] [not not :val]

Wonderful example of REBOL. :-)

The note is important, because that type restriction is the main 
reason for the function, as opposed to just using NOT NOT :val.

BrianH, this is in order to combat the use of unset! as inputs?

Yes.

I've backported most of R3 to R2 (it bears repeating, because it 
was a hell of a task). 67 functions so far.

Cool!

So does this mean a 2.7.7?

There is so much extra code done for R2, that I would be surprised 
if an R2.7.7, doesn't appear.

Just do one script and you can start porting your code. And it works 
in 2.6.2.

Perhaps it should be called 2.8 instead.

Since it is all mezzanines then I don't think it should be anything 
more than offered as a mezzanine library.

Keep the current version until new natives are developed.  Otherwise 
we get nothing but mezzanine bloat with the newer version.

I think as a minimum for a new version in REBOL - it should contain 
new natives.  Maybe Carl can make some of them natives.

Paul has deciphered the plan. I think it should stay a separate script. 
It breaks tons of R2 code. I expect that we won't be doing a 2.7.7 
soon, and when we do it will just be compatible bug fixes. The future 
compatibility stuff will be in the R2-Future collection.

I disagree with that plan, unless there will be a method to include 
all changes with a single line of code. There are also many additions 
in VID.

And no new natives in future R2 versions, just compatible fixes to 
errors in existing natives. The only changes will be to make less 
behavior cause errors. And you can include R2-Forward in one line 
of code now, in 2.6.2 even.

Are the VID changes in R2-Forward?

Brian, I suggest not waiting for Carl and just offer a library of 
 all the mezzanines that can be incorporated by just 'DOing the script 
to import them.

Carl, doesn't need to get diverted from his current R3 progress.

Paul, I am doing that already. I'm just waiting for approval to release 
them as MIT licensed code.

It's done already.

Don't know why you need approval.  Anyone should be able to release 
mezzanine code shouldn't they?

Mezzanine code has license restrictions. I can only release this 
at all because I wrote almost all of the original mezzanines and 
didn't assign copyright to REBOL Tech or Carl.

It didn't matter - I was going to open source it anyways.

I don't think you have any legal ramifications at all here.

There are a few functions that were originally written by Carl - 
7 of the 67 are slight tweaks to functions Carl wrote, the rest mine.

Everything is attributed in the file. The main difference in licensing 
is that you would not be restricted like REBOL mezzanine source. 
One of those restrictions is that it is not allowed to use mezzanine 
source (either in the SDK or the source function) on REBOL clones 
like Oscar.