Re: Quotations revisited

From	anton@mips.complang.tuwien.ac.at (Anton Ertl)
Newsgroups	comp.lang.forth
Subject	Re: Quotations revisited
Date	2012-07-16 14:05 +0000
Organization	Institut fuer Computersprachen, Technische Universitaet Wien
Message-ID	<2012Jul16.160531@mips.complang.tuwien.ac.at> (permalink)
References	<50031807.129829772@192.168.0.50> <58811288968435@frunobulax.edu>

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mhx@iae.nl (Marcel Hendrix) writes:
>Knuth's Man-Or-Boy test creates a quotation that *modifies* the 
>outer locals and then recursively calls its host, accessing outer 
>locals that one might have expected to long gone out of
>scope. It forces the quotation implementation to store copies of 
>*all imaginable* outer locals and make them permanently available.

For writable locals, it's a bad idea to make copies, because then any
write would need to write to all the copies.  The typical
implementation approach is to have a structure for each definition
that contains the direct locals of the definition; that structure is
called a frame or actication record.  The frame of an enclosed
definition links to the frame of the next-outer definition, and when
accessing an outer local, you follow the links until you are at the
right frame, and then perform the access.  Each frame has to be kept
around as long as it can be accessed (or typically, as long as there
is some link to it around).

There are optimizations of that optimization, with various tradeoffs.
E.g., if the locals are read-only, one can copy them.

>Maybe we first need a convincing example of the usefulness of 
>quotations and closures -- (*) would certainly be useful, but 
>the cost seems to be a little excessive?

Yes, the cost of closures seems excessive.  The cost of quotations
doesn't: no outer variables means no frames that have to be kept
around.

- 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 2012: http://www.euroforth.org/ef12/

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Quotations revisited mhx@iae.nl (Marcel Hendrix) - 2012-07-14 15:55 +0200
  Re: Quotations revisited stephenXXX@mpeforth.com (Stephen Pelc) - 2012-07-15 19:26 +0000
    Re: Quotations revisited Bernd Paysan <bernd.paysan@gmx.de> - 2012-07-15 23:53 +0200
    Re: Quotations revisited mhx@iae.nl (Marcel Hendrix) - 2012-07-15 23:54 +0200
      Re: Quotations revisited Bernd Paysan <bernd.paysan@gmx.de> - 2012-07-16 00:48 +0200
        Re: Quotations revisited Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-07-22 15:01 +0000
          Re: Quotations revisited anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-07-23 16:49 +0000
            Re: Quotations revisited Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-07-23 21:39 +0000
              Re: Quotations revisited anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-07-25 13:13 +0000
        Re: Quotations revisited Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-07-22 11:07 -0500
          Re: Quotations revisited Paul Rubin <no.email@nospam.invalid> - 2012-07-22 10:21 -0700
            Re: Quotations revisited Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-07-22 12:35 -0500
              Re: Quotations revisited Paul Rubin <no.email@nospam.invalid> - 2012-07-22 11:39 -0700
                Re: Quotations revisited Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-07-22 15:16 -0500
                Re: Quotations revisited Paul Rubin <no.email@nospam.invalid> - 2012-07-22 14:35 -0700
                Re: Quotations revisited Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-07-23 04:18 -0500
                Re: Quotations revisited Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-07-23 12:58 +0000
                Re: Quotations revisited Paul Rubin <no.email@nospam.invalid> - 2012-07-23 11:55 -0700
                Re: Quotations revisited BruceMcF <agila61@netscape.net> - 2012-07-23 05:45 -0700
            Re: Quotations revisited Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-07-27 12:41 +0000
      Re: Quotations revisited "Elizabeth D. Rather" <erather@forth.com> - 2012-07-15 14:11 -1000
        Re: Quotations revisited "A. K." <akk@nospam.org> - 2012-07-16 07:47 +0200
          Re: Quotations revisited anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-07-16 13:56 +0000
            Re: Quotations revisited "Elizabeth D. Rather" <erather@forth.com> - 2012-07-16 07:20 -1000
              Re: Quotations revisited anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-07-17 13:49 +0000
        Re: Quotations revisited Mark Wills <markrobertwills@yahoo.co.uk> - 2012-07-16 02:32 -0700
          Re: Quotations revisited Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-07-27 12:58 +0000
        Re: Quotations revisited Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-07-16 04:32 -0500
          Re: Quotations revisited stephenXXX@mpeforth.com (Stephen Pelc) - 2012-07-16 11:41 +0000
            Re: Quotations revisited Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-07-16 07:40 -0500
              Re: Quotations revisited stephenXXX@mpeforth.com (Stephen Pelc) - 2012-07-16 14:05 +0000
                Re: Quotations revisited Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-07-16 09:20 -0500
                Re: Quotations revisited stephenXXX@mpeforth.com (Stephen Pelc) - 2012-07-16 15:46 +0000
                Re: Quotations revisited Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-07-16 11:33 -0500
                Re: Quotations revisited anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-07-16 15:32 +0000
                Re: Quotations revisited stephenXXX@mpeforth.com (Stephen Pelc) - 2012-07-16 17:56 +0000
                Re: Quotations revisited Bernd Paysan <bernd.paysan@gmx.de> - 2012-07-16 23:37 +0200
          Re: Quotations revisited Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-07-27 13:05 +0000
            Re: Quotations revisited Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-07-27 08:21 -0500
      Re: Quotations revisited Roelf Toxopeus <rt4all@notthis.hetnet.nl> - 2012-07-16 10:14 +0200
      Re: Quotations revisited Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-07-16 04:23 -0500
        Re: Quotations revisited m.a.m.hendrix@tue.nl - 2012-07-16 03:39 -0700
          Re: Quotations revisited Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-07-16 07:09 -0500
            Re: Quotations revisited mhx@iae.nl (Marcel Hendrix) - 2012-07-16 23:47 +0200
              Re: Quotations revisited Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-07-17 04:14 -0500
                Re: Quotations revisited Coos Haak <chforth@hccnet.nl> - 2012-07-17 17:39 +0200
                Re: Quotations revisited Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-07-17 12:18 -0500
                Re: Quotations revisited mhx@iae.nl (Marcel Hendrix) - 2012-07-17 20:26 +0200
                Re: Quotations revisited anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-07-19 16:21 +0000
                Re: Quotations revisited Alex McDonald <blog@rivadpm.com> - 2012-07-19 15:58 -0700
      Re: Quotations revisited anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-07-16 14:05 +0000
    Re: Quotations revisited anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-07-16 12:47 +0000
      Re: Quotations revisited Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-07-16 08:56 -0500
      Re: Quotations revisited Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2012-07-16 15:04 +0100
        Re: Quotations revisited Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-07-16 09:23 -0500
          Re: Quotations revisited Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2012-07-16 17:38 +0100
            Re: Quotations revisited Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-07-16 12:58 -0500
        Re: Quotations revisited anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-07-16 14:56 +0000
      Re: Quotations revisited Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-07-16 22:53 +0000
        Re: Quotations revisited BruceMcF <agila61@netscape.net> - 2012-07-16 19:59 -0700
          Re: Quotations revisited "Elizabeth D. Rather" <erather@forth.com> - 2012-07-16 17:04 -1000
            Re: Quotations revisited anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-07-17 06:51 +0000
              Re: Quotations revisited "Elizabeth D. Rather" <erather@forth.com> - 2012-07-16 21:39 -1000
                Re: Quotations revisited anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-07-17 07:48 +0000
                Re: Quotations revisited "Elizabeth D. Rather" <erather@forth.com> - 2012-07-16 22:24 -1000
                Re: Quotations revisited anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-07-17 10:48 +0000
                Re: Quotations revisited "Elizabeth D. Rather" <erather@forth.com> - 2012-07-17 08:19 -1000
                Re: Quotations revisited Aleksej Saushev <asau@inbox.ru> - 2012-07-18 01:31 +0400
                Re: Quotations revisited anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-07-19 16:11 +0000
                Re: Quotations revisited "Elizabeth D. Rather" <erather@forth.com> - 2012-07-19 12:41 -1000
                Re: Quotations revisited Aleksej Saushev <asau@inbox.ru> - 2012-07-21 01:24 +0400
                Re: Quotations revisited "Elizabeth D. Rather" <erather@forth.com> - 2012-07-20 16:20 -1000
                Re: Quotations revisited Alex McDonald <blog@rivadpm.com> - 2012-07-21 03:59 -0700
                Re: Quotations revisited "Elizabeth D. Rather" <erather@forth.com> - 2012-07-21 21:33 -1000
                Re: Quotations revisited Alex McDonald <blog@rivadpm.com> - 2012-07-22 01:35 -0700
                Re: Quotations revisited Aleksej Saushev <asau@inbox.ru> - 2012-07-22 21:19 +0400
                Re: Quotations revisited "Elizabeth D. Rather" <erather@forth.com> - 2012-07-22 08:15 -1000
                Re: Quotations revisited Paul Rubin <no.email@nospam.invalid> - 2012-07-22 11:48 -0700
                Re: Quotations revisited Coos Haak <chforth@hccnet.nl> - 2012-07-22 21:48 +0200
                Re: Quotations revisited Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-07-22 15:22 -0500
                Re: Quotations revisited Paul Rubin <no.email@nospam.invalid> - 2012-07-22 14:50 -0700
                Re: Quotations revisited Paul Rubin <no.email@nospam.invalid> - 2012-07-22 15:08 -0700
                Re: Quotations revisited Alex McDonald <blog@rivadpm.com> - 2012-07-22 15:20 -0700
                Re: Quotations revisited Aleksej Saushev <asau@inbox.ru> - 2012-07-23 03:29 +0400
                Re: Quotations revisited "Elizabeth D. Rather" <erather@forth.com> - 2012-07-22 14:22 -1000
                Re: Quotations revisited Aleksej Saushev <asau@inbox.ru> - 2012-07-23 05:46 +0400
                Re: Quotations revisited "Elizabeth D. Rather" <erather@forth.com> - 2012-07-22 21:46 -1000
                Re: Quotations revisited Aleksej Saushev <asau@inbox.ru> - 2012-07-25 03:31 +0400
                Re: Quotations revisited anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-07-23 16:50 +0000
                Re: Quotations revisited "Elizabeth D. Rather" <erather@forth.com> - 2012-07-23 07:57 -1000
                Re: Quotations revisited Aleksej Saushev <asau@inbox.ru> - 2012-07-25 03:38 +0400
                Re: Quotations revisited anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-07-26 13:01 +0000
                Re: Quotations revisited Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-07-21 12:10 +0000
                Re: Quotations revisited Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-07-21 09:19 -0500
                Re: Quotations revisited Bernd Paysan <bernd.paysan@gmx.de> - 2012-07-21 18:58 +0200
                Re: Quotations revisited Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-07-22 04:24 -0500
                Re: Quotations revisited Bernd Paysan <bernd.paysan@gmx.de> - 2012-07-22 14:25 +0200
                Re: Quotations revisited Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-07-22 11:11 -0500
                Re: Quotations revisited Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-07-21 19:29 +0000
                Re: Quotations revisited anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-07-23 16:31 +0000
                Re: Quotations revisited Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-07-23 12:21 -0500
                Re: Quotations revisited anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-07-23 17:32 +0000
                Re: Quotations revisited Paul Rubin <no.email@nospam.invalid> - 2012-07-23 11:23 -0700
                Re: Quotations revisited Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-07-24 03:28 -0500
                Re: Quotations revisited anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-07-25 13:15 +0000
                Re: Quotations revisited Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-07-25 11:47 -0500
                Re: Quotations revisited anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-07-26 13:06 +0000
                Re: Quotations revisited Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-07-26 09:50 -0500
                Re: Quotations revisited anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-07-26 15:11 +0000
                Re: Quotations revisited Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-07-26 11:06 -0500
                Re: Quotations revisited anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-07-26 16:46 +0000
                Re: Quotations revisited Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-07-27 04:52 -0500
                Re: Quotations revisited Paul Rubin <no.email@nospam.invalid> - 2012-07-26 09:48 -0700
                Re: Quotations revisited anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-07-27 14:51 +0000
                Re: Quotations revisited Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-07-28 08:29 -0500
                Re: Quotations revisited Paul Rubin <no.email@nospam.invalid> - 2012-07-29 20:55 -0700
                Re: Quotations revisited Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-07-30 04:40 -0500
                Re: Quotations revisited anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-07-23 16:17 +0000
                Re: Quotations revisited "Rod Pemberton" <do_not_have@notemailnot.cmm> - 2012-07-22 18:41 -0400
                Re: Quotations revisited anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-07-23 16:53 +0000
            Re: Quotations revisited Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-07-17 12:22 +0000
              Re: Quotations revisited Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-07-17 07:30 -0500
                Re: Quotations revisited Alex McDonald <blog@rivadpm.com> - 2012-07-17 06:34 -0700
                Re: Quotations revisited Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-07-17 09:04 -0500
                Re: Quotations revisited Alex McDonald <blog@rivadpm.com> - 2012-07-18 07:07 -0700
                Re: Quotations revisited Coos Haak <chforth@hccnet.nl> - 2012-07-18 17:43 +0200
                Re: Quotations revisited Alex McDonald <blog@rivadpm.com> - 2012-07-18 09:29 -0700
                Re: Quotations revisited Coos Haak <chforth@hccnet.nl> - 2012-07-18 20:59 +0200
                Re: Quotations revisited Coos Haak <chforth@hccnet.nl> - 2012-07-18 21:14 +0200
                Re: Quotations revisited anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-07-19 16:05 +0000
                Re: Quotations revisited Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-07-20 14:50 +0000
                Re: Quotations revisited anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-07-20 15:08 +0000
                Re: Quotations revisited Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-07-21 11:27 +0000
                Re: Quotations revisited anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-07-23 16:28 +0000
                Re: Quotations revisited Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-07-23 19:41 +0000
                Re: Quotations revisited Alex McDonald <blog@rivadpm.com> - 2012-07-18 10:18 -0700
                Re: Quotations revisited anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-07-19 17:00 +0000
                Re: Quotations revisited Alex McDonald <blog@rivadpm.com> - 2012-07-19 15:34 -0700
                Re: Quotations revisited Alex McDonald <blog@rivadpm.com> - 2012-07-19 16:08 -0700
                Re: Quotations revisited Bernd Paysan <bernd.paysan@gmx.de> - 2012-07-17 20:09 +0200
  Re: Quotations revisited stephenXXX@mpeforth.com (Stephen Pelc) - 2012-07-16 12:01 +0000
    Re: Quotations revisited Paul Rubin <no.email@nospam.invalid> - 2012-07-16 10:42 -0700
      Re: Quotations revisited stephenXXX@mpeforth.com (Stephen Pelc) - 2012-07-16 18:06 +0000
        Re: Quotations revisited "Elizabeth D. Rather" <erather@forth.com> - 2012-07-16 11:08 -1000
          Re: Quotations revisited stephenXXX@mpeforth.com (Stephen Pelc) - 2012-07-16 21:38 +0000
            Re: Quotations revisited Bernd Paysan <bernd.paysan@gmx.de> - 2012-07-17 00:29 +0200
              Re: Quotations revisited "Elizabeth D. Rather" <erather@forth.com> - 2012-07-16 12:38 -1000
                Re: Quotations revisited Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-07-17 04:20 -0500
                Re: Quotations revisited Alex McDonald <blog@rivadpm.com> - 2012-07-17 03:21 -0700
                Re: Quotations revisited Alex McDonald <blog@rivadpm.com> - 2012-07-17 03:14 -0700
                Re: Quotations revisited Bernd Paysan <bernd.paysan@gmx.de> - 2012-07-17 19:58 +0200
                Re: Quotations revisited Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-07-17 13:05 -0500
  Re: Quotations revisited stephenXXX@mpeforth.com (Stephen Pelc) - 2012-07-20 11:12 +0000
    Re: Quotations revisited Alex McDonald <blog@rivadpm.com> - 2012-07-20 05:40 -0700
      Re: Quotations revisited stephenXXX@mpeforth.com (Stephen Pelc) - 2012-07-20 15:55 +0000
    Re: Quotations revisited Paul Rubin <no.email@nospam.invalid> - 2012-07-22 20:54 -0700
      Re: Quotations revisited Aleksej Saushev <asau@inbox.ru> - 2012-07-25 03:55 +0400

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