World: r3wp

Thanks.

I think that slice is much more general than the single string domains. 
So if introuduce it needs to be with care. Beside Graham if you are 
using a lot of substrings just create your own func it will make 
your code more explicit to your problem domain.

Record: [a b c d e f g h i]
foreach mold Record SeriesBlock [
   print record
]

Can someone tell me how to define a block (as in Record) and then 
use that variable in the foreach loop?
Although the array has values, nothing is printed in the loop.

When I remove the 'mold' statement, 'Record' contains just one value 
('a') not 9 (a b c d e f g h i).

>> foreach letter record [print letter]
a
b
c
d
e
f
g
h
i

okay?

Where is the 'block' argument?

>> help foreach
USAGE:
    FOREACH 'word data body

DESCRIPTION:
     Evaluates a block for each value(s) in a series.
     FOREACH is a native value.

ARGUMENTS:

     word -- Word or block of words to set each time (will be local) (Type: 
     get-word word block
)
     data -- The series to traverse (Type: series)
     body -- Block to evaluate each time (Type: block)

In this example,
WORD is letter
DATA is record
Body is [print letter]

I want to use two block arguments.  One for word (value that gets 
set each time) and of course the 'data' block.

Oh wait...

you can't with foreach!

actually you can.  Working example to follow

foreach [a b c d e f g h i] Datablock [ print [a b c d e f g h i]]

This traverses the datablock and sets each of the 9 values and prints 
them as a record.

However, I want to be able to set a variable instead of hardcoding 
"[a b c d e f g h i]"

ex: Record: array 9

then
foreach record datablock [ print record]

but when I do that, record doesn't contain an array of values

Sorry I don't understand what you want to do :-\

Oups, cross post

!> w: [a b]
== [a b]
!> foreach :w [1 2 3 4][? a ? b]
A is an integer of value: 1
B is an integer of value: 2
A is an integer of value: 3
B is an integer of value: 4

me too, and wrong.

okay just a minute

Ok, you want dynamic block of word to set, right?

Yiu can't have one variable -- you need a set of them, eg:
foreach [key data] ["a" 1232 "c" 7737 "z" 777] [print [key data]]
But you can fake it something like this......

data:  ["a" 1232 "c" 7737 "z" 777]
for nn 1 length? data 2 [print [pick data nn pick data nn + 1]]

record-sort: func [record [block!] num [integer!]] [
    tmp: copy []
    new: copy []
    foreach [a b c d] record [append/only tmp reduce [a b c d]]
    sort-method: func [a b] [(at a num) < (at b num)]
    foreach rec sort/compare tmp :sort-method [append new rec]
    return new
]


Here is the record-sort example given in the docs.  Problem is this 
only works for records that have four items.

the easier way is forskip. 'foreach needs a binding-trick

build the code then do it :)

Sunanda: Thanks for the example.  I'll play with your example and 
see what I can do.

Volker: Thanks.  I'll take a look at using forskip

why must it be in words?

The goal is to rewrite the record-sort function so that the number 
of elements is not hard coded into the function.

I want to be able to pass the function another value which equals 
the number of elements in a record and then do something like Record: 
array {Elements}

within the function.  This would make the function more universal.

>> print-n: func [record words] [do compose/deep [ foreach [(words)] 
record [print [(words)]]]]

>> print-n [1 2 3 4 5 6 7 8 9] [a b c]
1 2 3
4 5 6
7 8 9

forskip record 4 [append/only tmp copy/part record 4]

Humm.  That looks like it will work.

does sort/skip directly do what you want?

I'm not sure.  I don't think so but I can't remember why not.

Something about reordering the records makes sort/skip not suitable.

(Back to slicing briefly) REBOL already has functionality equivalent 
to slicing as copy-of-subsection, so this would be better represented 
as a very simple mezzanine function that does the work. If you mean 
slicing as reference-to-subsection-in-place, that would be worth 
adding new support for. Something like:

slice!: make object! [start: end: none]

slice: func [[catch] s [series!] /from b [integer!] /to e [integer!] 
/len l [integer!]] [
    b: either from [at :s b] [:s]
    e: case [
        to at :s e
        len skip :b l
        true tail :s
    ]
    if greater? index? :b index? :e [to: :e e: :b b: :to]
    make slice! [start: b end: e]
]

sort/skip --- I get you -- like it's not easy to sort on the 2-digit 
numbers here:
sort/skip [99 10 2       98 11 5        97 12 4] 3
But it is possible with /all and a parameter into the function

Lots to think about and try.  Thanks a bunch guys for your help.

When I get the function rewritten, I will upload it to the library.

Sunanda, do you mean sort on the second field? Try passing an integer 
or block of integers to the compare refinement of sort.

Rather than a comparator function.

I mean the middle of the three fields, sorting a 3-field record:
  sort-func: func [a b] [return a/2 < b/2]

  sort/skip/all/compare [99 10 2       98 11 5        97 12 4] 3 :sort-func
== [99 10 2 98 11 5 97 12 4]

sort/skip/compare data 3 2

The 2 passed to /comapare means the second field.

Clever -- I didn't know that. Thanks. 

But I tend to use the compare function to get stable sorts.  The 
[x < y]  was just  to shorten the example.