Re: Another recognizer discussion

From	anton@mips.complang.tuwien.ac.at (Anton Ertl)
Newsgroups	comp.lang.forth
Subject	Re: Another recognizer discussion
Date	2017-06-01 05:50 +0000
Organization	Institut fuer Computersprachen, Technische Universitaet Wien
Message-ID	<2017Jun1.075057@mips.complang.tuwien.ac.at> (permalink)
References	(1 earlier) <oghu89$mng$1@dont-email.me> <ogkmdp$prq$1@dont-email.me> <2017May31.132810@mips.complang.tuwien.ac.at> <ogmilq$bap$1@dont-email.me> <592f46a8.632823078@news.eternal-september.org>

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stephen@mpeforth.com (Stephen Pelc) writes:
>IMHO name tokens had a rationale for TRAVERSE-WORDLIST, but I was
>afraid that they would open the FIG-Forth can of worms that ANS
>nailed shut with the XT. Now we see that indeed NTs are rampant, but
>just replicating existing practice.

Can you elaborate on that?  Which can of worms do you mean?  Do you
think that FIND-NAME/SEARCH-NAME opens it, and if so, why?  I don't
understand what you mean with the last sentence at all.

>The whole point of an XT was to provide a single point of reference to
>a word. an XT is an opaque type (anything the implementation wants it
>to be). In many systems it's the address of the interpretation
>behaviour of the word - it's optimised for EXECUTE. The cost of 
>providing a link to a name field or name token is a single
>instruction on most desktop CPUs and even just one on most modern
>embedded CPUs.

In Gforth <=0.7 there is no reliable way to get to the name field, if
one even exists.  Do you want to disenfrenchise systems that are
implemented that way, and prescribe the implementation to provide a
link to the name field?

>The ghastliness of multiple xts for compilation actions is just
>exposing internal structures that should not be exposed. The idea
>of the ANS XT applies today just as much as did in 1994.

Your idea of xts is incompatible with ANS Forth.  Have you fixed VFX's
COMPILE, to be ANS Forth compliant already?  Remember, in ANS Forth
and Forth-2012 its stack effect is

COMPILE, ( xt -- )

I can dig out the bug report again that I sent you two years ago.

Anyway, there are Forth systems that have an xt for interpretation and
something independent for compilation, in order to implement words
such as S" (ANS Forth).  On these systems you cannot get to the
compilation semantics from the interpretation semantics (or vice
versa).  Do you want to disenfrenchise these systems by prescribing the
implementation?

>Other than
>for stepping through a wordlist, NTs offer nothing that cannot be
>provided by XTs.

An NT provides access to interpretation and compilation semantics, and
to the word name.

An XT can only be EXECUTEd and COMPILE,d; you cannot get the
interpretation and compilation semantics of a word from it in ANS
Forth or Forth-2012, nor the word name.  That is reflected in the
definition of FIND (ANS Forth and Forth-2012):

|For a given string, the values returned by FIND while compiling may
|differ from those returned while not compiling.

If the xt was the single point of reference to a word as you claim,
this sentence would make no sense.

- anton
-- 
M. Anton Ertl  http://www.complang.tuwien.ac.at/anton/home.html
comp.lang.forth FAQs: http://www.complang.tuwien.ac.at/forth/faq/toc.html
     New standard: http://www.forth200x.org/forth200x.html
   EuroForth 2017: http://www.euroforth.org/ef17/

Thread

Another recognizer discussion Alex <alex@rivadpm.com> - 2017-05-29 20:47 +0100
  Re: Another recognizer discussion Alex <alex@rivadpm.com> - 2017-05-29 20:57 +0100
    Re: Another recognizer discussion peter.m.falth@gmail.com - 2017-05-29 13:18 -0700
      Re: Another recognizer discussion Alex <alex@rivadpm.com> - 2017-05-29 22:47 +0100
      Re: Another recognizer discussion anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-05-30 07:43 +0000
    Re: Another recognizer discussion anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-05-30 07:30 +0000
    Re: Another recognizer discussion albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2017-05-30 09:53 +0200
    Re: Another recognizer discussion Alex <alex@rivadpm.com> - 2017-05-30 22:02 +0100
      Re: Another recognizer discussion peter.m.falth@gmail.com - 2017-05-31 01:27 -0700
        Re: Another recognizer discussion Alex <alex@rivadpm.com> - 2017-05-31 15:12 +0100
      Re: Another recognizer discussion minforth@arcor.de - 2017-05-31 03:43 -0700
        Re: Another recognizer discussion Alex <alex@rivadpm.com> - 2017-05-31 15:03 +0100
        Re: Another recognizer discussion anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-05-31 16:46 +0000
      Re: Another recognizer discussion anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-05-31 11:28 +0000
        Re: Another recognizer discussion anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-05-31 12:17 +0000
        Re: Another recognizer discussion Alex <alex@rivadpm.com> - 2017-05-31 15:10 +0100
          Re: Another recognizer discussion mhx@iae.nl - 2017-05-31 11:01 -0700
          Re: Another recognizer discussion stephen@mpeforth.com (Stephen Pelc) - 2017-05-31 22:55 +0000
            Re: Another recognizer discussion anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-06-01 05:50 +0000
              Re: Another recognizer discussion minforth@arcor.de - 2017-05-31 23:57 -0700
                Re: Another recognizer discussion anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-06-01 09:08 +0000
                Re: Another recognizer discussion minforth@arcor.de - 2017-06-01 03:33 -0700
              Re: Another recognizer discussion stephen@mpeforth.com (Stephen Pelc) - 2017-06-01 09:05 +0000
                Re: Another recognizer discussion Alex <alex@rivadpm.com> - 2017-06-01 15:05 +0100
                Re: Another recognizer discussion Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-06-01 10:05 -0500
                Re: Another recognizer discussion Alex <alex@rivadpm.com> - 2017-06-01 16:32 +0100
                Re: Another recognizer discussion Brad Eckert <hwfwguy@gmail.com> - 2017-06-01 09:31 -0700
                Re: Another recognizer discussion Alex <alex@rivadpm.com> - 2017-06-01 19:00 +0100
                Re: Another recognizer discussion stephen@mpeforth.com (Stephen Pelc) - 2017-06-04 22:56 +0000
                Re: Another recognizer discussion Alex <alex@rivadpm.com> - 2017-06-05 14:41 +0100
                Re: Another recognizer discussion Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-06-02 03:07 -0500
                Re: Another recognizer discussion anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-06-10 16:28 +0000
                Re: Another recognizer discussion Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-06-11 02:14 -0500
                Re: Another recognizer discussion anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-06-11 10:55 +0000
                Re: Another recognizer discussion Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-06-12 03:22 -0500
                Re: Another recognizer discussion anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-06-13 15:21 +0000
                Re: Another recognizer discussion Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-06-14 04:10 -0500
                Re: Another recognizer discussion anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-06-15 10:43 +0000
                Re: Another recognizer discussion Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-06-15 09:11 -0500
                Re: Another recognizer discussion minforth@arcor.de - 2017-06-14 02:55 -0700
                Re: Another recognizer discussion anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-06-14 10:19 +0000
                Re: Another recognizer discussion minforth@arcor.de - 2017-06-14 05:44 -0700
                Re: Another recognizer discussion stephen@mpeforth.com (Stephen Pelc) - 2017-06-14 14:27 +0000
                Re: Another recognizer discussion minforth@arcor.de - 2017-06-14 08:06 -0700
                Re: Another recognizer discussion stephen@mpeforth.com (Stephen Pelc) - 2017-06-14 16:36 +0000
                Re: Another recognizer discussion Brad Eckert <hwfwguy@gmail.com> - 2017-06-15 09:48 -0700
                Re: Another recognizer discussion stephen@mpeforth.com (Stephen Pelc) - 2017-06-15 17:18 +0000
                Re: Another recognizer discussion Alex <alex@rivadpm.com> - 2017-06-15 18:50 +0100
                Re: Another recognizer discussion stephen@mpeforth.com (Stephen Pelc) - 2017-06-15 19:22 +0000
                Re: Another recognizer discussion minforth@arcor.de - 2017-06-15 13:09 -0700
                Re: Another recognizer discussion Brad Eckert <hwfwguy@gmail.com> - 2017-06-15 13:43 -0700
                Re: Another recognizer discussion Lars Brinkhoff <lars.spam@nocrew.org> - 2017-06-15 22:55 +0200
                Re: Another recognizer discussion Alex <alex@rivadpm.com> - 2017-06-15 22:20 +0100
                pre-Rfd for smart word definition mechanism (was: Another ...) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-06-16 17:04 +0000
                Re: pre-Rfd for smart word definition mechanism (was: Another ...) stephen@mpeforth.com (Stephen Pelc) - 2017-06-16 21:58 +0000
                Re: pre-Rfd for smart word definition mechanism (was: Another ...) JennyB <jennybrien@googlemail.com> - 2017-06-17 00:26 -0700
                Re: pre-Rfd for smart word definition mechanism (was: Another ...) minforth@arcor.de - 2017-06-17 01:18 -0700
                Re: pre-Rfd for smart word definition mechanism (was: Another ...) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-06-17 15:24 +0000
                Re: pre-Rfd for smart word definition mechanism (was: Another ...) JennyB <jennybrien@googlemail.com> - 2017-06-17 12:29 -0700
                Re: pre-Rfd for smart word definition mechanism (was: Another ...) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-06-18 12:29 +0000
                Re: pre-Rfd for smart word definition mechanism (was: Another ...) albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2017-06-18 16:47 +0200
                Re: pre-Rfd for smart word definition mechanism (was: Another ...) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-06-17 10:20 +0000
                Re: Another recognizer discussion Brad Eckert <hwfwguy@gmail.com> - 2017-06-15 13:01 -0700
                Re: Another recognizer discussion anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-06-16 16:55 +0000
                Re: Another recognizer discussion stephen@mpeforth.com (Stephen Pelc) - 2017-06-16 17:40 +0000
                Re: Another recognizer discussion anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-06-16 16:47 +0000
                Re: Another recognizer discussion Brad Eckert <hwfwguy@gmail.com> - 2017-06-15 10:34 -0700
                Re: Another recognizer discussion anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-06-17 17:35 +0000
                Re: Another recognizer discussion peter.m.falth@gmail.com - 2017-06-17 15:24 -0700
                Re: Another recognizer discussion anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-06-18 12:00 +0000
                Re: Another recognizer discussion anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-06-16 12:29 +0000
                Re: Another recognizer discussion anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-06-16 07:35 +0000
                Re: Another recognizer discussion stephen@mpeforth.com (Stephen Pelc) - 2017-06-11 10:39 +0000
                Re: Another recognizer discussion Richard Owlett <rowlett@cloud85.net> - 2017-06-11 07:19 -0500
                Re: Another recognizer discussion anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-06-13 14:04 +0000
                Re: Another recognizer discussion stephen@mpeforth.com (Stephen Pelc) - 2017-06-14 12:50 +0000
                Re: Another recognizer discussion anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-06-15 16:19 +0000
                Re: Another recognizer discussion anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-06-02 07:59 +0000
                Re: Another recognizer discussion Lars Brinkhoff <lars.spam@nocrew.org> - 2017-06-02 11:48 +0200
                Re: Another recognizer discussion anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-06-02 10:24 +0000
                Re: Another recognizer discussion Lars Brinkhoff <lars.spam@nocrew.org> - 2017-06-02 13:04 +0200
                Re: Another recognizer discussion anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-06-02 13:30 +0000
                Re: Another recognizer discussion Lars Brinkhoff <lars.spam@nocrew.org> - 2017-06-02 16:36 +0200
                Re: Another recognizer discussion anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-06-02 15:51 +0000
                Re: Another recognizer discussion Lars Brinkhoff <lars.spam@nocrew.org> - 2017-06-02 21:09 +0200
                Re: Another recognizer discussion anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-06-01 15:55 +0000
                Re: Another recognizer discussion anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-06-01 14:21 +0000
                Re: Another recognizer discussion stephen@mpeforth.com (Stephen Pelc) - 2017-06-04 23:07 +0000
                Re: Another recognizer discussion anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-06-10 15:49 +0000
                Re: Another recognizer discussion stephen@mpeforth.com (Stephen Pelc) - 2017-06-11 11:14 +0000
                Re: Another recognizer discussion minforth@arcor.de - 2017-06-11 08:24 -0700
                Re: Another recognizer discussion anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-06-13 15:07 +0000
            Re: Another recognizer discussion Alex <alex@rivadpm.com> - 2017-06-01 12:11 +0100
  Re: Another recognizer discussion Matthias Trute <matthias.trute@gmail.com> - 2017-05-30 11:03 -0700

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