World: r3wp

So, no new operators.

and in fact XOR is the infamous ALTER.

Sorry Max, not at all.

ALTER is a modifying function.

yeah... tought about it and I was going to say... forget it.

modifying or not, its not doing the same thing anyways.

so I guess we only have to find an new function name for XOR's bitwise 
variant?

DIFFERENCE

ah, sorry, it would need to be the COMPLEMENT DIFFERENCE

or not, I confused it.

no it seems to work perfectly.  I just tried it.

(on blocks at least)

>> a: [1 2 3 4] b: [1 2 3 5]
== [1 2 3 5]
>> difference a b
== [4 5]

is exacty what I would expect of XOR on blocks.

>> difference make typeset! [none! unset! integer!] make typeset! 
[decimal! inte
ger! tuple!]
== make typeset! [unset! none! decimal! tuple!]


>> xor~ make typeset! [none! unset! integer!] make typeset! [decimal! 
integer! t
uple!]
== make typeset! [unset! none! decimal! tuple!]

So, yes, it should be DIFFERENCE

less words to learn and search in the dictionary.
the whole type 
system tries to build on this principle, so words can behave according 
to their context, just like in natural languages.

Agreed, this is key

I feel a little confused. Are you proposing that DIFFERENCE be used 
for bitwise XOR?

So logically:

>> (#"^(40)" xor #"^(C0)") = (difference #"^(40)" #"^(C0)")

I like the type adaptivity of REBOL and I build on it in all of my 
code, but in this case....


we have two completely different operations which can use the same 
datatypes in different ways... so there is no way to consolidate 
them.  hence this whole discussion

Are you proposing that DIFFERENCE be used for bitwise XOR?
 - I already wrote the ticket for it: http://issue.cc/r3/1879

But, unless you understand the difference between the conditional 
(NOT) and nonconditional (COMPLEMENT) operators, it is hard for you 
to find out what is going on.

the whole bitwise thing is pretty fucked up anyway. i tried to do 
a disk editor, a pic microcontroller HEX file processor, a custom 
serial communication protocol and in all cases i had to ping-pong 
between binary! issue! integer! and had to trim to the right bit/byte 
counts. it was a nightmare all the time.

it's big grief for me because rebol could be the bridge for hardware 
guys to the modern, internet connected world

no processing.org and arduino "C" crap..

now u want to apply set theory operation names to bitwise logic?

Yes, Tamas, it might be a good idea to suggest some improvements, 
if you are inclined to. You just need to realize, that there already 
are differences between the behaviour of R2 and R3.

:-)

it sounds very impractical to me...

sounds very impractical

 - well, my suggestion was based on the fact, that the UNION already 
 works as OR in many cases anyway.

As an example, see the comparison of XOR and DIFFERENCE above.

Ladislav: im back to the Rebol world since my new job allows me to 
use it. if i can secure my position in the next few month, i definitely 
will make exact suggestions

Of course, an alternative to use a completely different set of names 
can be considered as well.

Actually, I use bitiwse  XOR and OR to perform arithmetic on characters 
in my string encoding utilities script.

although having the set functions support the bitwise ops like they 
should...

I *also*I want bitwise infix ops... as long as the set functions 
to do the same arithmetic... basically just like how  'ADD  and  
'+  are equivalent.

If the broader problem would turn out to be unsolvable in the REBOL 
dialect, there will still be an R3 extension with a Red/System dialect

So, if I understand correctly, I would write someting like:

iso-ch: union #"^(40) utf-ch-2

and 

utf-ch: rejoin [#"^{C3}" difference #"^(40)" iso-ch]

- that is one possibility

It does look a little unusual but probably the equivalents with OR 
and XOR look odd to other people.

It's a long time since I studied set theory but if I remember correctly, 
the union of two sets is not dependant upon the order of the elements 
in a set.


So shouldn't the UNION of two sets of bits really be one of three 
values {0}. {1} or {0,1}.


I know this is knitpicking but I'm very used to XOR being bitwise.

Union appears to be implemented so in R3:

>> union [ 0 0 0 0 1 0 0 0] [ 0 0 0 1 0 0 0 0 ]
== [0 1]

Ladislav, http://issue.cc/r3/1879is a bit complicated when you consider 
that "operator" is used in REBOL jargon only for infix operations.
Your request looks like 3 related tickets:

- Extend the INTERSECT, UNION and DIFFERENCE functions to include 
the current bitwise behavior of AND, OR and XOR, respectively.
- Make operators for those functions (maybe &, | and ^).

- Change AND, OR and XOR operators (and AND~, OR~ and XOR~ functions) 
bitwise behavior to conditional behavior.
Is this a reasonable assessment of your request?

Peter, your right about the set functions and blocks. We should mention 
that in the ticket and say explicitly that these would not be set 
functions when applied to integers and such. The problem is that 
we would need bitwise operations to apply to strings and binaries 
as well, and these functions already treat them like sets. So there's 
a bit of functionality overlap that we have to deal with or else 
something will be lost.

your -> you're

The goal of having less dictionary entries to remember, and having 
the ops be smart, is valid; but in this case I think the meaning 
of the set op funcs (e.g. difference, union, etc.) are *much* clearer. 
Yes, most of us see AND and OR and know what's going on (though it 
sometimes makes my brain stutter a bit when debugging, especially 
XOR :-).

Having the set operations not act like set operations for some datatypes 
is only a little confusing - not much worse than what we have now. 
Losing either the setwise or the bitwise operations for strings and 
binaries is a much bigger problem - we need both, in different circumstances.

Sorry, just binaries. Good, I was worried that they might have tried 
to implement bitwise operations on R3 strings, which (conceptually) 
don't have a bitwise definition.

Though bitwise operations are allowed on chars, so that's a little 
inconsistent.

I think that not allowing bitwise operations on strings is a pragmatic 
restriction, because the internal data might get corrupted by them, 
and at the very least the results would be different depending on 
which internal storage mode is used. I'm not sure whether bitwise 
operations on characters currently work correctly at all, for the 
same reasons. What would be the proper behavior, and how can we check?

OK, just checked, characters are operated on as if they are integers 
of the same numeric values; that will do. We can't implement this 
in string form because we don't support UCS4 internally.

Note: COMPLEMENT doesn't support char!, probably because it would 
always result in characters that string! doesn't support, or even 
Unicode in many cases. This would continue to be the case with this 
proposal.