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World: r3wp

[Core] Discuss core issues

Graham
21-Aug-2009
[14522]
graham- findall "this is a test string" [ "this" "not here" ]
== none
Geomol
21-Aug-2009
[14523x2]
I guess joint is commonly used for marijuana


LOL, I didn't see that! (And I went to a Reggae festival last week, 
so I should know.) :-)
Do you want your function to find "ring" in this string: "this is 
a test string"?
Graham
21-Aug-2009
[14525]
yes
Sunanda
21-Aug-2009
[14526]
Geomol -- your code works only if the blocks are sorted, and contain 
no duplicates:
     findall [5 4 3 3 2 1] [3 2 1 1]
     == false
One way to fix that:

     findall: func [s items [block!]] [0 = length? exclude items intersect 
     s items]
     findall [5 4 3 3 2 1] [3 2 1 1]
     == true

But it does not help much with Graham's example which is looking 
for substrings :(
Geomol
21-Aug-2009
[14527]
What about this version?


findall: func [s items [block!]] [foreach i items [if not find s 
i [return false]] true]
Graham
21-Aug-2009
[14528x2]
I thought with map you can apply a function over all the parameters 
...
looks good
Geomol
21-Aug-2009
[14530x3]
Yes, you can with map, but you want it to stop, if one item isn't 
found, so not on all parameters.
Chris wrote: "G: re. confused - try stepping through the function 
in the order it is interpreted.  Should be clear by the time 'use 
evaluates the two blocks..."


What I find a bit confusing is, when I have to BIND and when I don't. 
It's the context binding rules in REBOL, that is not 100% clear to 
me. Let me give a simple example:

>> b: [print i]
== [print i]
>> f: has [i] [i: 1 do b]
>> f
** Script Error: i has no value


This doesn't work, because the b block is defined outside the f function, 
outside f's function context. Therefore I have to bind b to f's context, 
like this:

>> f: has [i] [i: 1 bind b 'i do b]
>> f
1


That is clear, and I would expect USE to work by the same rules, 
but it doesn't quite, it seems to me:

>> f: does [use [i] [i: 1 do b]]
>> f
1


By some magic, this works without the need to BIND. I'm a bit confused 
by that.
ARGH! It only works, because I first made the f function using BIND. 
So b was already bound to f, when I changed f to include USE. If 
I try to USE version from a fresh REBOL, it doesn't work. (More confusion!) 
:-p
Anton
21-Aug-2009
[14533x2]
Graham, I think your FINDALL is not well named. Just because it's 
using FIND doesn't mean it's doing the same thing. It should be more 
like COLLECT-ALL or COLLECT-EVERY.
Sorry, I'm wrong. Wrote too quickly.
Geomol
21-Aug-2009
[14535]
Ok, from a freshly started REBOL, this doesn't work:

>> b: [print i]
== [print i]
>> f: does [use [i] [i: 1 do b]]
>> f
** Script Error: i has no value

But this does work:

>> b: [print i]
== [print i]
>> f: does [use [i] reduce [to set-word! 'i 1 'do b]]
>> f
1


Is it because, when b is reduced, I kinda get a new fresh copy of 
the block? Like if I wrote the block, [print i], myself instead of 
using a reference to b?
Anton
21-Aug-2009
[14536]
REDUCE makes a new block, and then USE does its binding.
Geomol
21-Aug-2009
[14537]
Oki doki, that explains it.
Anton
21-Aug-2009
[14538x2]
BIND recurses into blocks, eg. 'b will be bound in the nested block 
[[b]],

but if 'b happens to currently have a value that is a block with 
words in it, that doesn't matter to BIND, BIND won't go in there.
Let me say that again, to be clear.

eg. Binding [[b]] somewhere will cause 'b to be bound (as long as 
'b exists in the "somewhere" context).

but if, before this bind occurs, b has a block value eg.  b: [some 
words] , then the bind will not touch 'some and 'words,

because it won't look to recurse into word values that happen to 
be blocks.
Geomol
22-Aug-2009
[14540]
How to check for a datatype using TYPE? within a function in REBOL 
2? Let's say, I wanted to create my own ACTION? function using TYPE?:

>> a?: func [value] [action! = type? value]
>> a? :action?
== false

Doesn't work. Does the logic work outside a function?

>> action! = type? :action?
== true

Yes. So maybe I need to specify the argument as a get-word! ?

>> a?: func [:value] [action! = type? value]
>> a? action?
== false

No, still doesn't work. Now on to REBOL 3 to see, how that work:

>> a?: func [value] [action! = type? value]
>> a? :action?
** Script error: value is missing its value argument

Huh? Trying with a get-word! :

>> a?: func [:value] [action! = type? value]
>> a? action?
== false

No, doesn't work. What am I missing? Or is it bugs?
Anton
22-Aug-2009
[14541]
Try this in the console:

	>> action?
	== false


No arguments were provided. The function can accept unset! values.
Geomol
22-Aug-2009
[14542x2]
Anyone got an old REBOL 1 lying around, I could have a look at?
Anton, ah, but my function doesn't work with other action! values 
anyway:

>> a?: func [:value] [action! = type? value]
>> a? first

** Script Error: value expected series argument of type: series pair 
event money date objec
t port time tuple any-function library struct ...

Trying dobble get-word! :

>> a? :first
== false

So maybe this doesn't work with any action! datatype?
Anton
22-Aug-2009
[14544x2]
It looks like your a? function evaluated the argument 'value. (I 
forget what get-word function parameters do...)
Works better like this:

	a?: func [value][action! = type? :value]
Better is
	a?: func [value][action? :value]
Geomol
22-Aug-2009
[14546x4]
>> a?: func [value] [action! = type? :value]
>> a? :action?
== true

Bravo!
My mistake. I get it now!
Thanks!
Anyone got an old REBOL 1 lying around, I could have a look at?
Anton
22-Aug-2009
[14550]
I noticed a get-word parameter prevents a paren argument value being 
evaluated first.
>> f: func [a][print mold a]
>> f (action?)
false
>> f: func [:a][print mold a]
>> f (action?)
(action?)
Geomol
22-Aug-2009
[14551x5]
Yeah, and you would probably like it to be mold :a in the function 
to not do the same mistake, I did. In your first example, you have 
evaluation of a two times, first as (action?) leading to false, and 
then false is evaluated when doing mold a.
Hey, I just read all that again. I can't figure out, why your second 
example returns (action?). That parenthesis should be evaluated, 
when you write mold a, shouldn't it?
It's the same in R3.
On the other hand, with the current behaviour, paren! works as block! 
in such situations. Blocks are not evaluated, when we write mold 
a, and a is a block. So why should a, if a is a paren! ? :-)
>> p: to paren! [a b c]
== (a b c)
>> mold p
== "(a b c)"

That's ok, I think.
Maxim
22-Aug-2009
[14556x2]
yep, we need that in order to handle things like parens in dialects.
>> a: [1 2 (3 4)]
== [1 2 (3 4)]
>> third a
== (3 4)
Ladislav
23-Aug-2009
[14558]
Geomol, I think, that you missed http://en.wikibooks.org/wiki/REBOL_Programming/Advanced/Interpreter
Geomol
23-Aug-2009
[14559]
Ladislav, how did you get the info to write that?
Ladislav
24-Aug-2009
[14560]
tests/experiments
Graham
25-Aug-2009
[14561x2]
Given some Json data like this::

{
page
:"1","total":4,"records":"22",
rows

:[{"id":null,"cell":["Quantum of Solace","Marc Forster","2008","Daniel 
Craig","200"]},

{"id":null,"cell":["Casino Royale","Martin Campbell","2006","Daniel 
Craig","150"]},

{"id":null,"cell":["Die Another Day","Lee Tamahori","2002","Pierce 
Brosnan","142"]},

{"id":null,"cell":["The World is Not Enough","Michael Apted","1999","Pierce 
Brosnan","135"]},

{"id":null,"cell":["Tomorrow Never Dies","Roger Spottiswoode","1997","Pierce 
Brosnan","110"]},

{"id":null,"cell":["GoldenEye","Martin Campbell","1995","Pierce Brosnan","58"]},

{"id":null,"cell":["Licence to Kill","John Glen","1989","Timothy 
Dalton","36"]}]
}


using Rebol-to-json, what sort of Rebol data object do I need to 
create to produce that output?
I've tried various combinations of objects and blocks and usually 
the rebol-to-json function just breaks.
Maxim
27-Aug-2009
[14563]
I am beyond mystified!   what is wrong with this code?

(1.3 * (any  [rgb clr]))


both rgb and clr have tuple values... if I remove the any, it works, 
if I try the any and probe it, it returns the proper value... 

this is within a compose block.

 ** Script Error: Cannot use multiply on decimal! value
** Where: refresh-gfx
** Near: 1.3 * (any [rgb clr])
PeterWood
27-Aug-2009
[14564x2]
Try reversing the operands to the *. It seems to work:

>> clr: 0.0.0             
== 0.0.0
>> rgb: 4.4.4             
== 4.4.4
>> 1.3 * (any [rgb clr])  
** Script Error: Cannot use multiply on decimal! value
** Near: 1.3 * (any [rgb clr])
>> ((any [rgb clr]) * 1.3)
== 5.5.5
Haven't figured out why :-)
Maxim
27-Aug-2009
[14566x2]
I can almost swear I tried it!  but anyhow I did the 'ANY earlier 
in the code.... and just use rgb directly now...
thanks for the help though... this is a really strange bug :-)
Sunanda
27-Aug-2009
[14568]
R2 does not allow [decimal! * tuple!] but it does allow [tuple! * 
decimal!] with a tuple! as the result
    1.3 * 9.9.9
    ** Script Error: Cannot use multiply on decimal! value
    9.9.9 * 1.3
    == 11.11.11

R3 allows both, with a tuple! as a result.

Looks like an R2 bug fixed only in R3.
Graham
27-Aug-2009
[14569x3]
In forming iso-8601 dates , you need to add the sign of the time 
zone.

Would you believe that 

pick [ "+" "-" ] positive? now/zone

is 4x faster than this

either (1 = (sign? now/zone)) ["+"] ["-"]
It relies on the behaviour of pick using false is same as pick 2
Is that going to be the same in R3?