World: r3wp

skip+: make function! [
    {Returns a series matching the skip sequence}
    series [series!] "Series to return skip values from."
    interval [integer!] "Skip interval"
    start [integer!] "Series index to start skipping from."
    /local blk
    ][
    blk: copy []
    if interval > (length? series) [return none]
    series: at series start
    while [not tail? series][

        if (index? series) = start [insert tail blk first series start: start 
        + interval]
        series: next series
    ]
    series: head series
    if empty? blk [return none]
    blk
]

Can I limit the end as well? Something like a SLICE?

not sure what you mean.

I have a long series of fixed width and need to extract starting 
from a current position backwad/forward the x-th value.

Your verison runs until the end of the series. I just need to skip 
the next 10 entries.

just copy that part of the series into a new series.

copy/part

I wanted to avoid the copy.

But OK.

:)

Is there an easy way to break out of a nested loop?

eg.

forever [
	forever [ 
		if true [ break outside both loops ]
	]
]

use throw and catch I guess

You could try to convert one of your loops to a function and do something 
like this:

>> y: func [] [             
[    forever [                
[        i: i + 1                 
[        print i                  
[        if i > 3 [return [break]]
[        ]
[    ]
>> i: 0
== 0
>> forever [do y]                                               
1
2
3
4

In other cases where you want ot break out of the inner loop, just 
return an empty block:

>> z: func [] [return []]
>> forever [do z]        
(escape)

Graham, catch and throw

hehe .. that's what I said

ah... yes

Continuing from Puzzle Answers. Isn't this a bit funny or strange?

First some failed attempts to make 2 a word of value 1:

>> 2: 1
** Syntax Error: Invalid time -- 2:
>> set '2 1
** Syntax Error: Invalid word-lit -- '2
>> set [2] 1 
** Script Error: Invalid argument: 2


So 2 shouldn't be a word. But then it's possible anyway with this 
trick:

>> set to-word "2" 1
== 1

2 is still a number:

>> 2
== 2

But 2 as a word exists:

>> get to-word "2"
== 1


I think, it's a bit strange. If it's intentional or not, I don't 
know.

the first behaviour (the error) would be the expected behaviour if 
you assume that base symbols such as number are protected from modification 
- this protection in R2 at least is not complete.

consider trying to audit code with blocks made in word form.. another 
source of insecurity / bugs

The only thing that blocks numbers to become word! values is the 
lexical scanner. When you type anything in console (or DO a file 
script), your input is first a string! value that gets LOADed (that's 
where the lexical scanner raises errors). TO-WORD allows to bypass 
the LOAD phase and force the conversion of any symbol to word! value.

Maybe it would be a good idea, if constructors like TO-WORD etc. 
would do a lexical scanning of the result?

Anyway, this gives us a probably unique method for strong code obfuscation. 
:-)

heh indeed!

heh, yeah! It's fun at times, but is it really a good idea?

the set to-word "2 + 2" with spaces is a bit of a worry

I agree, TO-WORD should enforce word! syntax rules on argument and 
raise syntax errors accordingly. That would be a more logical behavior. 
Maybe Carl had some design issues to workaround by allowing this 
(or maybe it's just an implementation flaw).

>> set to-word " " "secret"
== "secret"
>> blk: reduce [to-word " "]
== [ ]
>> reduce blk
== ["secret"]

Good one! Nothing can be something in REBOL. :-)

There is no spoon
 or "The truth is elsewhere" could make nice REBOL baselines. ;-)

R3 however does do a whitespace check thankfully

whitespace characters appear invalid in words in R3 - although if 
they are able to be redefined that could be an issue/weakness

Geomol <funny or strange>

It gets odder ( or less consistent) as '+ does seem to be given special 
handing......

What I really wanted to do to solve the puzzle was:
    -- set to-word "2" 5
    -- set to-word "+" none
The block then becomes (in effect)
   do [5 none 5]
   == 5
      

But DOing the gimmicked block in R2 fell found of '+ being both a 
native and some hardwired syntax in the interpreter:

    set to-word "2" 5
    set to-word "+" none
    blk: copy []
    blk: reduce [to-word "2" to-word "+" to-word "2"]
    probe blk
        == [2 + 2]
    do blk
        ** Script Error: Invalid operator: +
        ** Near: 2 + 2

In R2 the operators are special-cased by DO. In R3 they handle themselves 
(quicker that way).

Wouldn't it be nice to do:

series: [1 2 3 4 5 6 7 8 9 10]

find series > 5

such that it returns:

[6 7 8 9 10]

Even extend that to use CHAR values also.

I agree that adding a refinement to include a compare func would 
be pretty usefull!

maybe some other func provides this and we're not thinking about 
it.

Seem I'm always wanting this functionality and would be a very useful 
upgrade.

Could be Maxim, I often put something down - only to find Gabriele 
or Ladislav showing me another way.

there is something like filter function I think (or you can make 
one that takes values and expression)

I know we can easily build a function to do this but it seems so 
well suited to the 'find function.

find/match series (6 =  pick serie 1)

would make a lot of sense to me.

In R3:
 
remove-each x series [x <= 5]

We ave remove-each in R2 also but that is a bit different as it is 
doing removal - I don't want something removed just a subset returned.

I submitted my request to cure-code.

yess remove actuall modifies the series being given, find just changes 
its offest.

it would be more like extract with a /find index.

You could copy the series first, although obviously this impacts 
performance.