From Newsgroup: comp.lang.forth

- DOxxx performs the loop
- Indices are integers.
- forms of DO
one-bound {BODY} DO) \ 0 ... one-bound-1
one-bound {BODY} DO] \ 1 ... one-bound
b1 b2 {BODY} DO[] \ b1 .. b2
b1 b2 stride {BODY} DO[..] \ b1 b1+stride b1+2*stride .. b2

Maybe
b1 b2 {BODY} DO[) \ b1 .. b2-1
to accommodate
array length OVER + {BODY} DO[)

Note the stride is now constant obviously.
If it is negative, the loop goes down.
If you want to straddle from positive to negative (addresses?),
program it explicitly and conspicuously.

Note 1
The [ ) convention comes from mathematics, example:
[1,9] interval 1 2 3 4 5 6 7 8 9
[1,9) interval 1 2 3 4 5 6 7 8
(0,9) interval 1 2 3 4 5 6 7 8

Note 2
{BODY} leans heavily on [: ;] presence. (Or ciforth's { } )

Note 3
If you want to change the stride mid-program, you have to
use BEGIN WHILE REPEAT, as you should have done in the first place.

The four DO's replace the four don't's : ?DO DO LOOP +LOOP .

Groetjes Albert
--
Don't praise the day before the evening. One swallow doesn't make spring.
You must not say "hey" before you have crossed the bridge. Don't sell the
hide of the bear until you shot it. Better one bird in the hand than ten in
the air. First gain is a cat purring. - the Wise from Antrim -
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From Newsgroup: comp.lang.forth

Also handy When you have list types:

(( 1 2 3 5 7 11 13 17 )) DO-WITH ..

or

(( H2 O2 CO CO2 )) DO-WITH ..
where H2 et al can be numbers/addresses or arrays/strings
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From Newsgroup: comp.lang.forth

On 14/03/2024 12:30 am, albert@spenarnc.xs4all.nl wrote:

- DOxxx performs the loop
- Indices are integers.
- forms of DO
one-bound {BODY} DO) \ 0 ... one-bound-1
one-bound {BODY} DO] \ 1 ... one-bound
b1 b2 {BODY} DO[] \ b1 .. b2
b1 b2 stride {BODY} DO[..] \ b1 b1+stride b1+2*stride .. b2

Maybe
b1 b2 {BODY} DO[) \ b1 .. b2-1
to accommodate
array length OVER + {BODY} DO[)

Note the stride is now constant obviously.
If it is negative, the loop goes down.
If you want to straddle from positive to negative (addresses?),
program it explicitly and conspicuously.

Note 1
The [ ) convention comes from mathematics, example:
[1,9] interval 1 2 3 4 5 6 7 8 9
[1,9) interval 1 2 3 4 5 6 7 8
(0,9) interval 1 2 3 4 5 6 7 8

Note 2
{BODY} leans heavily on [: ;] presence. (Or ciforth's { } )

Note 3
If you want to change the stride mid-program, you have to
use BEGIN WHILE REPEAT, as you should have done in the first place.

The four DO's replace the four don't's : ?DO DO LOOP +LOOP .

All these alternatives to DO LOOP that folks propose don't get off the
ground because the 'lesser programmers' for whom they're intended don't eventuate.

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