Re: Coroutines in Forth

From	Gerry Jackson <do-not-use@swldwa.uk>
Newsgroups	comp.lang.forth
Subject	Re: Coroutines in Forth
Date	2026-04-08 12:32 +0100
Organization	A noiseless patient Spider
Message-ID	<10r5ed7$3hakr$1@dont-email.me> (permalink)
References	<10qunhm$1nnbt$1@dont-email.me> <10r1825$2d8j6$1@dont-email.me> <nnd$7d2e6a4e$3bd4aa4f@294189cda32d8f1f> <10r3nfo$33464$1@dont-email.me> <nnd$1df5c626$6d97c61c@066801e65fcbf8a0>

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On 08/04/2026 11:34, albert@spenarnc.xs4all.nl wrote:
> In article <10r3nfo$33464$1@dont-email.me>,
> Gerry Jackson  <do-not-use@swldwa.uk> wrote:
>> On 07/04/2026 12:35, albert@spenarnc.xs4all.nl wrote:
>>> A similar situation applies to "TO must scan". It turns out there
>>> is no standard program that can detect this. It steers implementation
>>> towards a scanning TO.
>>
>> On the contrary, Ruvim posted some code that is a standard program and
>> which distinguises between a parsing TO and one that sets a flag for a
>> following VALUE to act on.
>>
>> I can't find the post but the gist of it was (I think):
>>
>> 1 value v1
>> 2 value v2 immediate
>> : test  to v2 v1  ;
>> Running test with
>> 3 test
>> A parsing TO will set v2 to 3
>> A flagging TO will execute v2 during compilation of test because it is
>> immediate. So test will set v1 to 3 leaving v2 unchanged.
> 
> No it doesn't. It leaves garbage on the stack during compilation,
> leading to mostly an error.

Do you mean your system does that?

My mistake, I should have written:
A flagging TO should ...

> I leave it up to the reader whether this counts as a standard program.

Contrived test or not it is standard.
> 
> I overlooked this clever example.
As did everybody else until Ruvim devised it.

> So I guess my VALUE is non compliant, proven by a contrived test.

Yes

> 
> It still makes no sense to forbid a flagging implementation.

I have some sympathy with that but it does ensure that TO has to be on 
the same line as the value name and that the value name does occur 
immediately after the TO as there can be multiple TOs in succession or 
other intervening code (provided TO doesn't leave garbage on the stack).
Anyway surely a flagging TO is slower as it has to test the flag?

> (Also VALUE's don't make sense, anyway.)

VALUEs make more sense than some other things in the standard!

-- 
Gerry

Thread

Coroutines in Forth Gerry Jackson <do-not-use@swldwa.uk> - 2026-04-05 23:25 +0100
  Re: Coroutines in Forth Gerry Jackson <do-not-use@swldwa.uk> - 2026-04-05 23:30 +0100
    Re: Coroutines in Forth Paul Rubin <no.email@nospam.invalid> - 2026-04-05 17:16 -0700
      Re: Coroutines in Forth Gerry Jackson <do-not-use@swldwa.uk> - 2026-04-06 19:58 +0100
        Re: Coroutines in Forth Paul Rubin <no.email@nospam.invalid> - 2026-04-22 11:13 -0700
          Re: Coroutines in Forth albert@spenarnc.xs4all.nl - 2026-04-22 22:05 +0200
      Re: Coroutines in Forth albert@spenarnc.xs4all.nl - 2026-04-07 13:23 +0200
  Re: Coroutines in Forth albert@spenarnc.xs4all.nl - 2026-04-06 13:51 +0200
    Re: Coroutines in Forth Gerry Jackson <do-not-use@swldwa.uk> - 2026-04-06 22:20 +0100
      Re: Coroutines in Forth albert@spenarnc.xs4all.nl - 2026-04-07 13:35 +0200
        Re: Coroutines in Forth Gerry Jackson <do-not-use@swldwa.uk> - 2026-04-07 20:55 +0100
          Re: Coroutines in Forth albert@spenarnc.xs4all.nl - 2026-04-08 12:34 +0200
            Re: Coroutines in Forth Gerry Jackson <do-not-use@swldwa.uk> - 2026-04-08 12:32 +0100
            non-parsing `TO` considered harmful Ruvim <ruvim.pinka@gmail.com> - 2026-06-04 22:26 +0000
              Re: non-parsing `TO` considered harmful Ruvim <ruvim.pinka@gmail.com> - 2026-06-06 12:54 +0000
                Re: non-parsing `TO` considered harmful anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-06-06 16:17 +0000
                Re: non-parsing `TO` considered harmful Ruvim <ruvim.pinka@gmail.com> - 2026-06-06 21:09 +0000
                Re: non-parsing `TO` considered harmful anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-06-07 13:23 +0000
                Re: non-parsing `TO` considered harmful Ruvim <ruvim.pinka@gmail.com> - 2026-06-07 17:44 +0000
                Re: non-parsing `TO` considered harmful anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-06-08 05:04 +0000
                text translator (was: non-parsing `TO` considered harmful) Ruvim <ruvim.pinka@gmail.com> - 2026-06-08 15:53 +0000
                Recognizers vs Parsing words (was: non-parsing `TO` considered harmful) Ruvim <ruvim.pinka@gmail.com> - 2026-06-09 10:25 +0000
                Re: Recognizers vs Parsing words Ruvim <ruvim.pinka@gmail.com> - 2026-06-10 19:45 +0000
                compilation of compilation (was: non-parsing `TO` considered harmful) Ruvim <ruvim.pinka@gmail.com> - 2026-06-08 07:28 +0000
                Recognizer API v.2025-09-11 (was: non-parsing `TO` considered harmful) Ruvim <ruvim.pinka@gmail.com> - 2026-06-14 12:41 +0000
                Re: Recognizer API v.2025-09-11 (was: non-parsing `TO` considered harmful) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-06-15 17:17 +0000
                Re: Recognizer API v.2025-09-11 Ruvim <ruvim.pinka@gmail.com> - 2026-06-16 17:34 +0000
                Re: Recognizer API v.2025-09-11 anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-06-17 05:05 +0000
                Setters and getters in APIs (was: Recognizer API v.2025-09-11) Ruvim <ruvim.pinka@gmail.com> - 2026-06-19 16:17 +0000
                Re: Setters and getters in APIs (was: Recognizer API v.2025-09-11) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-06-20 15:51 +0000
                Re: non-parsing `TO` considered harmful Stephen Pelc <stephen@vfxforth.com> - 2026-06-07 11:59 +0000
                Re: non-parsing `TO` considered harmful anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-06-07 15:25 +0000
          Re: Coroutines in Forth Stephen Pelc <stephen@vfxforth.com> - 2026-04-09 10:12 +0000
            non-parsing `TO` considered harmful Ruvim <ruvim.pinka@gmail.com> - 2026-06-04 22:30 +0000
              VFX Forth problems Ruvim <ruvim.pinka@gmail.com> - 2026-06-05 16:24 +0000
            Re: Coroutines in Forth marcel hendrix <mhx@iae.nl> - 2026-07-09 09:50 +0200
              Re: Coroutines in Forth albert@SPENARNC.XS4ALL.NL - 2026-07-10 01:48 +0200
          Re: Coroutines in Forth Stephen Pelc <stephen@vfxforth.com> - 2026-06-07 11:53 +0000
            non-parsing `TO` considered harmful (was: Coroutines in Forth) Ruvim <ruvim.pinka@gmail.com> - 2026-06-07 13:31 +0000
              Re: non-parsing `TO` considered harmful Travis Bemann <tabemann@gmail.com> - 2026-08-28 20:36 -0500
        Re: Coroutines in Forth Hans Bezemer <the.beez.speaks@gmail.com> - 2026-04-10 19:01 +0200
          Re: Coroutines in Forth dxf <dxforth@gmail.com> - 2026-04-11 11:54 +1000
            Re: Coroutines in Forth Hans Bezemer <the.beez.speaks@gmail.com> - 2026-05-01 13:07 +0200
          Re: Coroutines in Forth peter <peter.noreply@tin.it> - 2026-04-11 09:49 +0200
          Re: Coroutines in Forth albert@spenarnc.xs4all.nl - 2026-04-11 22:03 +0200
            Re: Coroutines in Forth dxf <dxforth@gmail.com> - 2026-04-12 12:49 +1000
              Re: Coroutines in Forth albert@spenarnc.xs4all.nl - 2026-04-12 12:13 +0200
                Re: Coroutines in Forth Hans Bezemer <the.beez.speaks@gmail.com> - 2026-04-12 17:39 +0200
                Re: Coroutines in Forth dxf <dxforth@gmail.com> - 2026-04-13 10:54 +1000
                Re: Coroutines in Forth Hans Bezemer <the.beez.speaks@gmail.com> - 2026-04-13 19:24 +0200
              Re: Coroutines in Forth Hans Bezemer <the.beez.speaks@gmail.com> - 2026-04-12 13:48 +0200
              Re: Coroutines in Forth albert@spenarnc.xs4all.nl - 2026-04-13 12:13 +0200
              Re: Coroutines in Forth Paul Rubin <no.email@nospam.invalid> - 2026-04-22 11:18 -0700
                Re: Coroutines in Forth dxf <dxforth@gmail.com> - 2026-04-23 11:13 +1000
                Re: Coroutines in Forth Hans Bezemer <the.beez.speaks@gmail.com> - 2026-04-23 12:37 +0200
                Re: Coroutines in Forth Paul Rubin <no.email@nospam.invalid> - 2026-04-24 10:36 -0700
                Re: Coroutines in Forth dxf <dxforth@gmail.com> - 2026-04-25 12:12 +1000
                Re: Coroutines in Forth Paul Rubin <no.email@nospam.invalid> - 2026-04-24 23:31 -0700
                Re: Coroutines in Forth albert@spenarnc.xs4all.nl - 2026-04-25 10:45 +0200
                Re: Coroutines in Forth dxf <dxforth@gmail.com> - 2026-04-25 22:06 +1000
                Re: Coroutines in Forth Hans Bezemer <the.beez.speaks@gmail.com> - 2026-04-25 15:11 +0200
                Re: Coroutines in Forth dxf <dxforth@gmail.com> - 2026-04-26 13:33 +1000
                Re: Coroutines in Forth Hans Bezemer <the.beez.speaks@gmail.com> - 2026-04-26 16:28 +0200
                Re: Coroutines in Forth Paul Rubin <no.email@nospam.invalid> - 2026-04-25 21:46 -0700
                FP stack depth limitations (was: Coroutines in Forth) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-04-26 05:55 +0000
                Re: FP stack depth limitations Paul Rubin <no.email@nospam.invalid> - 2026-04-26 00:28 -0700
                Re: FP stack depth limitations dxf <dxforth@gmail.com> - 2026-04-26 19:55 +1000
                Re: FP stack depth limitations (was: Coroutines in Forth) peter <peter.noreply@tin.it> - 2026-04-26 09:57 +0200
                Re: FP stack depth limitations (was: Coroutines in Forth) albert@spenarnc.xs4all.nl - 2026-04-26 14:34 +0200
                Re: Coroutines in Forth Hans Bezemer <the.beez.speaks@gmail.com> - 2026-04-25 15:01 +0200
                Re: Coroutines in Forth Hans Bezemer <the.beez.speaks@gmail.com> - 2026-05-01 13:13 +0200
                Forth, C, hardware, and programming virtues (was: Coroutines in Forth) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-04-25 05:26 +0000
                Re: Forth, C, hardware, and programming virtues Paul Rubin <no.email@nospam.invalid> - 2026-04-24 23:55 -0700
                Re: Forth, C, hardware, and programming virtues anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-04-25 08:21 +0000
                Re: Forth, C, hardware, and programming virtues albert@spenarnc.xs4all.nl - 2026-04-25 11:27 +0200
                Re: Forth, C, hardware, and programming virtues Hans Bezemer <the.beez.speaks@gmail.com> - 2026-04-25 15:43 +0200
                Re: Forth, C, hardware, and programming virtues anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-04-25 17:21 +0000
                Re: Forth, C, hardware, and programming virtues dxf <dxforth@gmail.com> - 2026-04-26 15:21 +1000
                Re: Forth, C, hardware, and programming virtues Hans Bezemer <the.beez.speaks@gmail.com> - 2026-04-26 15:08 +0200
                Re: Forth, C, hardware, and programming virtues albert@spenarnc.xs4all.nl - 2026-04-26 00:34 +0200
                Re: Forth, C, hardware, and programming virtues Hans Bezemer <the.beez.speaks@gmail.com> - 2026-04-26 15:10 +0200
                locals (was: Coroutines in Forth) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-04-25 04:47 +0000
                Re: locals Paul Rubin <no.email@nospam.invalid> - 2026-04-24 23:21 -0700
                Re: locals anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-04-25 06:43 +0000
                Re: locals albert@spenarnc.xs4all.nl - 2026-04-25 11:43 +0200
                Re: locals anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-04-25 10:22 +0000
                Re: locals peter <peter.noreply@tin.it> - 2026-04-25 16:07 +0200
                Re: locals Hans Bezemer <the.beez.speaks@gmail.com> - 2026-04-25 17:38 +0200
                Re: locals albert@spenarnc.xs4all.nl - 2026-04-26 01:13 +0200
                Re: locals anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-04-26 14:03 +0000
                Re: locals peter <peter.noreply@tin.it> - 2026-04-27 09:31 +0200
                Re: locals anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-04-27 07:53 +0000
                Re: locals peter <peter.noreply@tin.it> - 2026-04-27 11:52 +0200
                Re: locals albert@spenarnc.xs4all.nl - 2026-04-26 00:51 +0200
                Re: locals Paul Rubin <no.email@nospam.invalid> - 2026-04-25 22:40 -0700
                Re: locals albert@spenarnc.xs4all.nl - 2026-04-26 14:55 +0200
                Re: locals anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-04-26 09:50 +0000
                Re: locals Hans Bezemer <the.beez.speaks@gmail.com> - 2026-04-26 16:22 +0200
                Re: locals anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-04-26 17:04 +0000
                Re: locals dxf <dxforth@gmail.com> - 2026-04-27 11:51 +1000
                Re: locals Hans Bezemer <the.beez.speaks@gmail.com> - 2026-04-28 08:21 +0200
                Re: locals Hans Bezemer <the.beez.speaks@gmail.com> - 2026-04-28 08:22 +0200
                Re: locals dxf <dxforth@gmail.com> - 2026-04-27 11:12 +1000
                Re: locals Hans Bezemer <the.beez.speaks@gmail.com> - 2026-04-28 14:34 +0200
                Re: locals Hans Bezemer <the.beez.speaks@gmail.com> - 2026-04-28 14:34 +0200
                Re: locals Gerry Jackson <do-not-use@swldwa.uk> - 2026-04-29 12:44 +0100
                Re: locals Hans Bezemer <the.beez.speaks@gmail.com> - 2026-04-29 14:37 +0200
                Re: locals Hans Bezemer <the.beez.speaks@gmail.com> - 2026-04-29 14:44 +0200
                Re: locals Paul Rubin <no.email@nospam.invalid> - 2026-05-01 23:50 -0700
                Re: locals anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-05-02 10:34 +0000
                Re: locals Paul Rubin <no.email@nospam.invalid> - 2026-05-01 23:54 -0700
                Re: locals dxf <dxforth@gmail.com> - 2026-05-02 17:36 +1000
                Re: locals Paul Rubin <no.email@nospam.invalid> - 2026-05-02 01:11 -0700
                Re: locals anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-05-02 15:58 +0000
      Re: Coroutines in Forth Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-04-07 09:28 -0500
        Re: Coroutines in Forth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-04-07 16:12 +0000
          Re: Coroutines in Forth Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-04-07 18:06 -0500
          Re: Coroutines in Forth Gerry Jackson <do-not-use@swldwa.uk> - 2026-04-08 11:43 +0100
            Re: Coroutines in Forth albert@spenarnc.xs4all.nl - 2026-04-08 13:16 +0200
              Re: Coroutines in Forth Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-04-08 11:47 -0500
                Re: Coroutines in Forth Gerry Jackson <do-not-use@swldwa.uk> - 2026-04-08 21:48 +0100
                Re: Coroutines in Forth Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-04-09 07:06 -0500
                Re: Coroutines in Forth albert@spenarnc.xs4all.nl - 2026-04-09 16:41 +0200
                Re: Coroutines in Forth Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-04-09 13:34 -0500
                Re: Coroutines in Forth albert@spenarnc.xs4all.nl - 2026-04-10 01:23 +0200
                Re: Coroutines in Forth Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-04-09 21:34 -0500
                Re: Coroutines in Forth albert@spenarnc.xs4all.nl - 2026-04-09 13:01 +0200
                Re: Coroutines in Forth Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-04-09 07:01 -0500
                Re: Coroutines in Forth albert@spenarnc.xs4all.nl - 2026-04-09 16:10 +0200
                Re: Coroutines in Forth Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-04-09 13:29 -0500
              Re: Coroutines in Forth Gerry Jackson <do-not-use@swldwa.uk> - 2026-04-08 21:26 +0100
          Re: Coroutines in Forth Hans Bezemer <the.beez.speaks@gmail.com> - 2026-04-08 14:22 +0200
          Re: Coroutines in Forth Hans Bezemer <the.beez.speaks@gmail.com> - 2026-04-28 15:31 +0200
            Re: Coroutines in Forth albert@spenarnc.xs4all.nl - 2026-04-29 10:49 +0200
              Re: Coroutines in Forth Hans Bezemer <the.beez.speaks@gmail.com> - 2026-04-29 15:22 +0200
        Re: Coroutines in Forth Gerry Jackson <do-not-use@swldwa.uk> - 2026-04-08 11:33 +0100
          Re: Coroutines in Forth albert@spenarnc.xs4all.nl - 2026-04-08 13:07 +0200
            Re: Coroutines in Forth Gerry Jackson <do-not-use@swldwa.uk> - 2026-04-08 22:05 +0100
  Re: Coroutines in Forth albert <albert@spenarnc.xs4all.nl> - 2026-06-21 01:26 +0200

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