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Groups > comp.lang.c > #53464 > unrolled thread
| Started by | Rosario193 <Rosario@invalid.invalid> |
|---|---|
| First post | 2014-11-26 21:54 +0100 |
| Last post | 2014-12-19 02:34 +0100 |
| Articles | 20 on this page of 177 — 31 participants |
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the language Rosario193 <Rosario@invalid.invalid> - 2014-11-26 21:54 +0100
Re: the language Rosario193 <Rosario@invalid.invalid> - 2014-11-26 21:56 +0100
Re: the language John Bode <jfbode1029@gmail.com> - 2014-11-26 13:45 -0800
Re: the language Rosario193 <Rosario@invalid.invalid> - 2014-11-28 11:52 +0100
Re: the language "Bill Cunningham" <nospam@nspam.invalid> - 2014-12-01 23:25 -0500
Re: the language "Bill Cunningham" <nospam@nspam.invalid> - 2014-12-02 00:56 -0500
Re: the language Rosario193 <Rosario@invalid.invalid> - 2014-12-04 14:52 +0100
Re: the language "Osmium" <r124c4u102@comcast.net> - 2014-12-04 08:07 -0600
Re: the language Geoff <geoff@invalid.invalid> - 2014-12-04 10:20 -0800
Re: the language Mark Storkamp <mstorkamp@yahoo.com> - 2014-11-26 15:11 -0600
Re: the language Rosario193 <Rosario@invalid.invalid> - 2014-11-28 12:16 +0100
Re: the language Rosario193 <Rosario@invalid.invalid> - 2014-11-28 12:18 +0100
Re: the language John Bode <jfbode1029@gmail.com> - 2014-11-26 13:12 -0800
Re: the language Kaz Kylheku <kaz@kylheku.com> - 2014-11-27 00:37 +0000
Re: the language Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-11-27 01:13 +0000
Re: the language raltbos@xs4all.nl (Richard Bos) - 2014-11-26 22:45 +0000
Re: the language Rosario193 <Rosario@invalid.invalid> - 2014-11-27 07:41 +0100
Re: the language Rosario193 <Rosario@invalid.invalid> - 2014-11-27 08:12 +0100
Re: the language Morris Dovey <mrdovey@iedu.com> - 2014-11-27 01:43 -0600
Re: the language Rosario193 <Rosario@invalid.invalid> - 2014-11-28 11:56 +0100
Re: the language Morris Dovey <mrdovey@iedu.com> - 2014-11-28 09:08 -0600
Re: the language Rosario193 <Rosario@invalid.invalid> - 2014-11-28 20:58 +0100
Re: the language Morris Dovey <mrdovey@iedu.com> - 2014-11-28 19:22 -0600
Re: the language Rosario193 <Rosario@invalid.invalid> - 2014-12-02 02:59 +0100
Re: the language Kaz Kylheku <kaz@kylheku.com> - 2014-12-02 02:53 +0000
Re: the language Les Cargill <lcargill99@comcast.com> - 2014-12-01 21:25 -0600
Re: the language Kaz Kylheku <kaz@kylheku.com> - 2014-12-02 06:22 +0000
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-11-27 08:37 +0000
Re: the language Reinhardt Behm <rbehm@hushmail.com> - 2014-11-27 16:44 +0800
Re: the language gazelle@shell.xmission.com (Kenny McCormack) - 2014-11-27 15:35 +0000
Re: the language Richard Damon <Richard@Damon-Family.org> - 2014-11-27 11:58 -0500
Re: the language jt@toerring.de (Jens Thoms Toerring) - 2014-11-27 22:44 +0000
Re: the language Rosario193 <Rosario@invalid.invalid> - 2014-11-28 09:52 +0100
Re: the language Tim Rentsch <txr@alumni.caltech.edu> - 2014-11-28 12:53 -0800
Re: the language Thomas Jahns <jahns@idontlikespam.dkrz.de> - 2014-11-28 10:07 +0100
Re: the language Thomas Jahns <jahns@idontlikespam.dkrz.de> - 2014-11-28 14:57 +0100
Re: the language Tim Rentsch <txr@alumni.caltech.edu> - 2014-11-28 13:09 -0800
Re: the language Rosario193 <Rosario@invalid.invalid> - 2014-11-28 12:01 +0100
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-11-28 14:46 +0000
Re: the language Tim Rentsch <txr@alumni.caltech.edu> - 2014-11-28 13:16 -0800
Re: the language gazelle@shell.xmission.com (Kenny McCormack) - 2014-11-28 22:09 +0000
Re: the language Tim Rentsch <txr@alumni.caltech.edu> - 2014-12-01 03:40 -0800
Re: the language Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-11-28 14:42 -0800
Re: the language Tim Rentsch <txr@alumni.caltech.edu> - 2014-12-01 03:22 -0800
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-11-28 23:09 +0000
Re: the language Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-11-28 16:14 -0800
Re: the language BartC <bc@freeuk.com> - 2014-11-29 01:42 +0000
Re: the language Kaz Kylheku <kaz@kylheku.com> - 2014-11-29 01:42 +0000
Re: the language Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-11-29 04:03 -0800
Re: the language Keith Thompson <kst-u@mib.org> - 2014-12-01 00:55 -0800
Re: the language glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-12-02 05:42 +0000
Re: the language Richard Damon <Richard@Damon-Family.org> - 2014-11-28 19:25 -0500
Re: the language Tim Rentsch <txr@alumni.caltech.edu> - 2014-12-01 03:21 -0800
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-01 14:02 +0000
Re: the language Tim Rentsch <txr@alumni.caltech.edu> - 2014-12-05 10:18 -0800
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-07 08:25 +0000
Re: the language Öö Tiib <ootiib@hot.ee> - 2014-12-07 10:44 -0800
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-07 19:17 +0000
Re: the language Öö Tiib <ootiib@hot.ee> - 2014-12-07 15:48 -0800
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-08 05:45 +0000
Re: the language Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-12-08 03:27 -0800
Re: the language Kaz Kylheku <kaz@kylheku.com> - 2014-12-08 06:00 +0000
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-08 06:17 +0000
Re: the language Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-12-08 03:37 -0800
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-08 12:53 +0000
Re: the language Tim Rentsch <txr@alumni.caltech.edu> - 2014-12-16 04:21 -0800
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-16 12:43 +0000
Re: the language Tim Rentsch <txr@alumni.caltech.edu> - 2014-12-16 14:46 -0800
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-17 00:23 +0000
Re: the language JohnF <john@please.see.sig.for.email.com> - 2014-12-17 07:01 +0000
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-17 07:22 +0000
Re: the language Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-12-17 11:56 +0000
Re: the language Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-12-17 05:43 -0800
Re: the language Rosario193 <Rosario@invalid.invalid> - 2014-12-18 18:30 +0100
Re: the language Rosario193 <Rosario@invalid.invalid> - 2014-12-18 18:41 +0100
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-17 14:34 +0000
Re: the language Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-12-18 02:15 +0000
Re: the language James Kuyper <jameskuyper@verizon.net> - 2014-12-17 22:31 -0500
Re: the language Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-12-18 17:19 +0000
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-18 07:52 +0000
Re: the language Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-12-18 17:21 +0000
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-18 18:15 +0000
Re: the language Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-12-19 01:20 +0000
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-19 07:48 +0000
Re: the language James Kuyper <jameskuyper@verizon.net> - 2014-12-19 07:40 -0500
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-19 12:54 +0000
Re: the language James Kuyper <jameskuyper@verizon.net> - 2014-12-19 09:54 -0500
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-19 15:19 +0000
Re: the language James Kuyper <jameskuyper@verizon.net> - 2014-12-19 11:00 -0500
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-19 16:13 +0000
Re: the language James Kuyper <jameskuyper@verizon.net> - 2014-12-19 11:27 -0500
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-19 16:45 +0000
Re: the language James Kuyper <jameskuyper@verizon.net> - 2014-12-19 13:48 -0500
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-19 19:10 +0000
Re: the language Morris Dovey <mrdovey@iedu.com> - 2014-12-19 21:17 -0600
Re: the language Morris Dovey <mrdovey@iedu.com> - 2014-12-19 21:32 -0600
Re: the language Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-12-19 16:49 +0000
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-19 17:00 +0000
Re: the language James Kuyper <jameskuyper@verizon.net> - 2014-12-19 13:57 -0500
Re: the language Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-12-19 14:31 -0800
Re: the language Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-12-19 20:29 +0000
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-19 20:36 +0000
Re: the language Tim Rentsch <txr@alumni.caltech.edu> - 2014-12-17 07:18 -0800
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-17 15:45 +0000
Re: the language glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-12-17 16:50 +0000
Re: the language raltbos@xs4all.nl (Richard Bos) - 2014-12-17 17:24 +0000
Re: the language Robert Wessel <robertwessel2@yahoo.com> - 2014-12-18 02:07 -0600
Re: the language raltbos@xs4all.nl (Richard Bos) - 2014-12-18 12:04 +0000
Re: the language Richard Damon <Richard@Damon-Family.org> - 2014-12-18 08:06 -0500
Re: the language James Kuyper <jameskuyper@verizon.net> - 2014-12-18 08:30 -0500
Re: the language Richard Damon <Richard@Damon-Family.org> - 2014-12-19 00:11 -0500
Re: the language glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-12-19 07:00 +0000
Re: the language Keith Thompson <kst-u@mib.org> - 2014-12-19 08:43 -0800
Re: the language Richard Damon <Richard@Damon-Family.org> - 2014-12-19 23:29 -0500
Re: the language Keith Thompson <kst-u@mib.org> - 2014-12-20 00:37 -0800
Re: the language gazelle@shell.xmission.com (Kenny McCormack) - 2014-12-20 08:45 +0000
Re: the language raltbos@xs4all.nl (Richard Bos) - 2014-12-20 09:45 +0000
Re: the language Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-12-20 03:17 -0800
Re: the language Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-12-18 06:09 -0800
Re: the language raltbos@xs4all.nl (Richard Bos) - 2014-12-18 14:30 +0000
Re: the language raltbos@xs4all.nl (Richard Bos) - 2014-12-18 14:23 +0000
Re: the language Keith Thompson <kst-u@mib.org> - 2014-12-18 08:18 -0800
Re: the language Richard Damon <Richard@Damon-Family.org> - 2014-12-20 12:22 -0500
Re: the language James Kuyper <jameskuyper@verizon.net> - 2014-12-20 13:36 -0500
Re: the language Keith Thompson <kst-u@mib.org> - 2014-12-20 11:43 -0800
Re: the language Keith Thompson <kst-u@mib.org> - 2014-12-20 11:37 -0800
Re: the language glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-12-20 20:10 +0000
Re: the language Robert Wessel <robertwessel2@yahoo.com> - 2014-12-21 15:02 -0600
Re: the language Kaz Kylheku <kaz@kylheku.com> - 2014-12-21 22:02 +0000
Re: the language Stephen Sprunk <stephen@sprunk.org> - 2014-12-21 23:49 -0600
Re: the language raltbos@xs4all.nl (Richard Bos) - 2014-12-21 17:45 +0000
Re: the language Tim Rentsch <txr@alumni.caltech.edu> - 2014-12-18 10:29 -0800
Re: the language Robert Wessel <robertwessel2@yahoo.com> - 2014-12-20 05:29 -0600
Re: the language Tim Rentsch <txr@alumni.caltech.edu> - 2014-12-20 11:32 -0800
Re: the language Robert Wessel <robertwessel2@yahoo.com> - 2014-12-21 15:23 -0600
Re: the language Tim Rentsch <txr@alumni.caltech.edu> - 2014-12-22 23:39 -0800
Re: the language glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-12-20 20:22 +0000
Re: the language Tim Rentsch <txr@alumni.caltech.edu> - 2014-12-18 10:24 -0800
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-18 18:36 +0000
Re: the language Tim Rentsch <txr@alumni.caltech.edu> - 2014-12-19 09:24 -0800
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-19 17:53 +0000
Re: the language Tim Rentsch <txr@alumni.caltech.edu> - 2014-12-20 11:48 -0800
Re: the language JohnF <john@please.see.sig.for.email.com> - 2014-12-19 02:20 +0000
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-19 08:31 +0000
Re: the language JohnF <john@please.see.sig.for.email.com> - 2014-12-19 09:31 +0000
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-19 10:10 +0000
Re: the language Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-12-19 07:08 -0800
Re: the language JohnF <john@please.see.sig.for.email.com> - 2014-12-20 06:39 +0000
Re: the language John Forkosh <forkosh@panix.com> - 2014-12-20 07:32 +0000
Re: the language Greg Martin <greg.at.softsprocket@dot.com> - 2015-01-04 17:02 +0000
Re: the language James Kuyper <jameskuyper@verizon.net> - 2015-01-04 12:40 -0500
Re: the language Greg Martin <greg.at.softsprocket@dot.com> - 2015-01-04 18:02 +0000
Re: the language James Kuyper <jameskuyper@verizon.net> - 2015-01-05 09:47 -0500
Re: the language Greg Martin <greg.at.softsprocket@dot.com> - 2015-01-05 15:14 +0000
Re: the language Keith Thompson <kst-u@mib.org> - 2015-01-05 08:42 -0800
Re: the language glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-01-06 00:14 +0000
Re: the language James Kuyper <jameskuyper@verizon.net> - 2015-01-05 13:19 -0500
Re: the language Richard Damon <Richard@Damon-Family.org> - 2015-01-04 15:59 -0500
Re: the language Keith Thompson <kst-u@mib.org> - 2015-01-04 14:30 -0800
Re: the language Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-01-04 15:44 -0800
Re: the language James Kuyper <jameskuyper@verizon.net> - 2015-01-05 13:36 -0500
Re: the language Rosario193 <Rosario@invalid.invalid> - 2014-11-28 12:07 +0100
Re: the language "ocq (an evil corporate man)" <ocq@maili.ng> - 2014-12-02 23:16 +0100
Re: the language Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-12-03 02:23 -0800
Re: the language "ocq (an evil corporate man)" <ocq@maili.ng> - 2014-12-03 15:55 +0100
Re: the language Nobody <nobody@nowhere.invalid> - 2014-12-03 15:42 +0000
Re: the language Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-12-04 04:49 -0800
Re: the language Keith Thompson <kst-u@mib.org> - 2014-12-04 09:07 -0800
Re: the language Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-12-04 10:08 -0800
Re: the language Keith Thompson <kst-u@mib.org> - 2014-12-04 11:49 -0800
Re: the language Rosario193 <Rosario@invalid.invalid> - 2014-12-05 12:32 +0100
Re: the language raltbos@xs4all.nl (Richard Bos) - 2014-12-04 22:17 +0000
Re: the language Rosario193 <Rosario@invalid.invalid> - 2014-12-18 18:17 +0100
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-18 18:12 +0000
Re: the language Rosario193 <Rosario@invalid.invalid> - 2014-12-18 23:15 +0100
Re: the language Rosario193 <Rosario@invalid.invalid> - 2014-12-18 23:50 +0100
Re: the language "ocq (an evil corporate man)" <ocq@maili.ng> - 2014-12-19 02:34 +0100
Page 4 of 9 — ← Prev page 1 2 3 [4] 5 6 7 8 9 Next page →
| From | Malcolm McLean <malcolm.mclean5@btinternet.com> |
|---|---|
| Date | 2014-12-08 03:27 -0800 |
| Message-ID | <81510427-d853-4fa9-bc4f-1fcbf8880f9b@googlegroups.com> |
| In reply to | #54052 |
On Sunday, December 7, 2014 11:48:42 PM UTC, Öö Tiib wrote: > > How? Let me try another analogy. There is a universe with every rule of > nature clearly set and fully determined. Like game of life just > significantly more complex. What is the reason to call it uninteresting universe? > That's not possible. Assuming that your game of life board can be arbitrarily large, and you can run as many steps as you want, there's a trivial mapping from a game of life universe to any other deterministic universe and vice versa.
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| From | Kaz Kylheku <kaz@kylheku.com> |
|---|---|
| Date | 2014-12-08 06:00 +0000 |
| Message-ID | <20141207215252.421@kylheku.com> |
| In reply to | #54026 |
On 2014-12-07, Richard Heathfield <invalid@see.sig.invalid> wrote: > Tim Rentsch wrote: > >> Can you define what is meant for a language >> to be interesting in such a way that undefined behavior is >> not inherently built into the definition? > > No, I don't think I can, but that doesn't (necessarily, at least) mean I'm > wrong - it just means I'm struggling to define a fairly nebulous concept. > But a language in which every string is either illegal or well-defined > would, it seems to me, tend to make it more difficult to innovate in ways > unanticipated by the language designer. Ah, but what if some strings have the special function of opening escape hatches which are closed by default? For instance, integer oveflow can be diagnosed, by default. But some syntax can request that it be undefined. Of course this then means that there are strings of the language that have undefined behavior. Namely strings which are made up of substrings which open an escape hatch, and other substrings which use it. However, the situation is such that the hatches are managed, so those who want to write programs without them (whose ideal language has no hatches) just about have that. Furthermore, those users can be given a master option: one which produce a loud diagnostic if any escape hatches are used (and pinpoint their locations). Effectively, in that mode, the language is a dialect free of UB.
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| From | Richard Heathfield <invalid@see.sig.invalid> |
|---|---|
| Date | 2014-12-08 06:17 +0000 |
| Message-ID | <dobhw.14457$N92.2480@fx31.am4> |
| In reply to | #54061 |
Kaz Kylheku wrote: > On 2014-12-07, Richard Heathfield <invalid@see.sig.invalid> wrote: >> Tim Rentsch wrote: >> >>> Can you define what is meant for a language >>> to be interesting in such a way that undefined behavior is >>> not inherently built into the definition? >> >> No, I don't think I can, but that doesn't (necessarily, at least) mean >> I'm wrong - it just means I'm struggling to define a fairly nebulous >> concept. But a language in which every string is either illegal or >> well-defined would, it seems to me, tend to make it more difficult to >> innovate in ways unanticipated by the language designer. > > Ah, but what if some strings have the special function of opening > escape hatches which are closed by default? > > For instance, integer oveflow can be diagnosed, by default. But some > syntax can request that it be undefined. > > Of course this then means that there are strings of the language that > have undefined behavior. Namely strings which are made up of substrings > which open an escape hatch, and other substrings which use it. > > However, the situation is such that the hatches are managed, so those > who want to write programs without them (whose ideal language has no > hatches) > just about have that. Furthermore, those users can be given a master > option: one which produce a loud diagnostic if any escape hatches are used > (and pinpoint their locations). Effectively, in that mode, the language is > a dialect free of UB. A: "How many angels can dance on the head of a pin?" B: "There might not be a pin." A: "True, but I have a plan for that..." Yes, perhaps we can re-define undefined behaviour in such a way as to eliminate it, but we haven't actually changed anything other than the way we describe the behaviour. We still need to be able to open new doors if we are going to journey to new places. -- Richard Heathfield Email: rjh at cpax dot org dot uk "Usenet is a strange place" - dmr 29 July 1999 Sig line 4 vacant - apply within
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| From | Malcolm McLean <malcolm.mclean5@btinternet.com> |
|---|---|
| Date | 2014-12-08 03:37 -0800 |
| Message-ID | <9236d562-93b6-4083-a2dd-8ff9bba80663@googlegroups.com> |
| In reply to | #54062 |
On Monday, December 8, 2014 6:17:54 AM UTC, Richard Heathfield wrote: > > Yes, perhaps we can re-define undefined behaviour in such a way as to > eliminate it, but we haven't actually changed anything other than the way we > describe the behaviour. We still need to be able to open new doors if we are > going to journey to new places. > We can shuffle bits about in the memory, and undefined behaviour is just a nuisance to us. You can talk endlessly about bit shuffling, you can do degrees and take doctorates in it, build your entire career purely around questions of how to transform one set of init bits to another set of output bits. But it's entirely useless unless the bits are somehow connected to something outside the computer's memory. That's where we must have undefined behaviour, it's inherently impossible to say how a system connected to the outside world will behave, purely from looking at the system and ignoring the outside world.
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| From | Richard Heathfield <invalid@see.sig.invalid> |
|---|---|
| Date | 2014-12-08 12:53 +0000 |
| Message-ID | <obhhw.16249$484.4819@fx46.am4> |
| In reply to | #54077 |
Malcolm McLean wrote: > On Monday, December 8, 2014 6:17:54 AM UTC, Richard Heathfield wrote: >> >> Yes, perhaps we can re-define undefined behaviour in such a way as to >> eliminate it, but we haven't actually changed anything other than the way >> we describe the behaviour. We still need to be able to open new doors if >> we are going to journey to new places. >> > We can shuffle bits about in the memory, and undefined behaviour is just a > nuisance to us. You can talk endlessly about bit shuffling, you can do > degrees and take doctorates in it, build your entire career purely around > questions of how to transform one set of init bits to another set of > output bits. > > But it's entirely useless unless the bits are somehow connected to > something outside the computer's memory. That's where we must have > undefined behaviour, it's inherently impossible to say how a system > connected to the outside world will behave, purely from looking at the > system and ignoring the outside world. Well put. It wasn't until I acquired a printer that I was able to look upon my Atari ST as anything more than a neat toy... and the C Standard doesn't define interfaces to printers. Had I been aware at the time of ANSI C (ISO C was yet to come), I would have looked upon this as a grave shortcoming in the Standard. Now I know better, of course. The Standard steers well clear of hardware for the excellent reason that you never know what's round the next corner. (Actually, nowadays you /can/ know, thanks to car bumper cameras, but the C Standard doesn't specify an interface to those, either.) -- Richard Heathfield Email: rjh at cpax dot org dot uk "Usenet is a strange place" - dmr 29 July 1999 Sig line 4 vacant - apply within
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| From | Tim Rentsch <txr@alumni.caltech.edu> |
|---|---|
| Date | 2014-12-16 04:21 -0800 |
| Message-ID | <kfnfvcfbx9y.fsf@x-alumni2.alumni.caltech.edu> |
| In reply to | #54026 |
Richard Heathfield <invalid@see.sig.invalid> writes:
> Tim Rentsch wrote:
>
>> Can you define what is meant for a language
>> to be interesting in such a way that undefined behavior is
>> not inherently built into the definition?
>
> No, I don't think I can,
In that case the conclusion is devoid of any meaningful content. In
effect the situation we are in is where we have
definition (partial): a language is interesting only if it has
elements with undefined behavior
and then want to consider the assertion (or hypothesis) that if a
language has no undefined behavior, then it is not sufficiently
powerful to be interesting. That assertion is most assuredly true
under that partial definition. It also is true that is it not
sufficiently weak to be interesting, or sufficiently anything to be
interesting, because if it has no undefined behavior then by
definition it isn't interesting.
> but that doesn't (necessarily, at least) mean I'm wrong [snip]
As things stand the conclusion is neither wrong nor right,
because no meaning has been assigned to the notion of what
constitutes an interesting language. Until that happens,
the question is, quite literally, meaningless.
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| From | Richard Heathfield <invalid@see.sig.invalid> |
|---|---|
| Date | 2014-12-16 12:43 +0000 |
| Message-ID | <WNVjw.79225$AC.77361@fx29.am4> |
| In reply to | #54675 |
Tim Rentsch wrote: > Richard Heathfield <invalid@see.sig.invalid> writes: > >> Tim Rentsch wrote: >> >>> Can you define what is meant for a language >>> to be interesting in such a way that undefined behavior is >>> not inherently built into the definition? >> >> No, I don't think I can, > > In that case the conclusion is devoid of any meaningful content. In > effect the situation we are in is where we have > > definition (partial): a language is interesting only if it has > elements with undefined behavior > > and then want to consider the assertion (or hypothesis) that if a > language has no undefined behavior, then it is not sufficiently > powerful to be interesting. That assertion is most assuredly true > under that partial definition. It also is true that is it not > sufficiently weak to be interesting, or sufficiently anything to be > interesting, because if it has no undefined behavior then by > definition it isn't interesting. > >> but that doesn't (necessarily, at least) mean I'm wrong [snip] > > As things stand the conclusion is neither wrong nor right, > because no meaning has been assigned to the notion of what > constitutes an interesting language. Until that happens, > the question is, quite literally, meaningless. Or rather, it is intractable, because we don't have a commonly-agreed set of term definitions. So let me try to step around the intractability by re- casting my argument in a slightly different way: A language in which every possible construct is either well-defined or illegal makes it very difficult for programmers to add kinds of functionality unanticipated by the language designers. -- Richard Heathfield Email: rjh at cpax dot org dot uk "Usenet is a strange place" - dmr 29 July 1999 Sig line 4 vacant - apply within
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| From | Tim Rentsch <txr@alumni.caltech.edu> |
|---|---|
| Date | 2014-12-16 14:46 -0800 |
| Message-ID | <kfnmw6n9prx.fsf@x-alumni2.alumni.caltech.edu> |
| In reply to | #54678 |
Richard Heathfield <invalid@see.sig.invalid> writes: > Tim Rentsch wrote: > >> Richard Heathfield <invalid@see.sig.invalid> writes: >> >>> Tim Rentsch wrote: >>> >>>> Can you define what is meant for a language >>>> to be interesting in such a way that undefined behavior is >>>> not inherently built into the definition? >>> >>> No, I don't think I can, >> >> In that case the conclusion is devoid of any meaningful content. In >> effect the situation we are in is where we have >> >> definition (partial): a language is interesting only if it has >> elements with undefined behavior >> >> and then want to consider the assertion (or hypothesis) that if a >> language has no undefined behavior, then it is not sufficiently >> powerful to be interesting. That assertion is most assuredly true >> under that partial definition. It also is true that is it not >> sufficiently weak to be interesting, or sufficiently anything to be >> interesting, because if it has no undefined behavior then by >> definition it isn't interesting. >> >>> but that doesn't (necessarily, at least) mean I'm wrong [snip] >> >> As things stand the conclusion is neither wrong nor right, >> because no meaning has been assigned to the notion of what >> constitutes an interesting language. Until that happens, >> the question is, quite literally, meaningless. > > Or rather, it is intractable, because we don't have a > commonly-agreed set of term definitions. So let me try to step > around the intractability by re- casting my argument in a > slightly different way: > > A language in which every possible construct is either > well-defined or illegal makes it very difficult for programmers > to add kinds of functionality unanticipated by the language > designers. I have a suspicion that we are getting close to a philosophical question about what is meant by behavior being defined (or undefined). I would rather not enter such a philosphical discussion. However I will mention something just for the benefit of your interest in the question, and not intending to make any sort of point in argument (so please accept it in that spirit). The note is simply that, in C, I would put the system() library function in the category of defined behavior, not undefined behavior.
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| From | Richard Heathfield <invalid@see.sig.invalid> |
|---|---|
| Date | 2014-12-17 00:23 +0000 |
| Message-ID | <024kw.130013$O%4.76090@fx39.am4> |
| In reply to | #54770 |
Tim Rentsch wrote: > Richard Heathfield <invalid@see.sig.invalid> writes: > >> Tim Rentsch wrote: >> <snip> >>> As things stand the conclusion is neither wrong nor right, >>> because no meaning has been assigned to the notion of what >>> constitutes an interesting language. Until that happens, >>> the question is, quite literally, meaningless. >> >> Or rather, it is intractable, because we don't have a >> commonly-agreed set of term definitions. So let me try to step >> around the intractability by re- casting my argument in a >> slightly different way: >> >> A language in which every possible construct is either >> well-defined or illegal makes it very difficult for programmers >> to add kinds of functionality unanticipated by the language >> designers. > > I have a suspicion that we are getting close to a philosophical > question about what is meant by behavior being defined (or > undefined). I would rather not enter such a philosphical > discussion. Frankly, that makes two of us. > However I will mention something just for the > benefit of your interest in the question, and not intending to > make any sort of point in argument (so please accept it in > that spirit). The note is simply that, in C, I would put > the system() library function in the category of defined > behavior, not undefined behavior. It's a well-chosen example, insofar as it demonstrates clearly that we think very differently from each other on this matter. I'm out. -- Richard Heathfield Email: rjh at cpax dot org dot uk "Usenet is a strange place" - dmr 29 July 1999 Sig line 4 vacant - apply within
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| From | JohnF <john@please.see.sig.for.email.com> |
|---|---|
| Date | 2014-12-17 07:01 +0000 |
| Message-ID | <m6r9p1$kl0$1@reader1.panix.com> |
| In reply to | #54770 |
Tim Rentsch <txr@alumni.caltech.edu> wrote: > Richard Heathfield <invalid@see.sig.invalid> writes: >> <<snip>> >> A language in which every possible construct is either >> well-defined or illegal makes it very difficult for programmers >> to add kinds of functionality unanticipated by the language >> designers. > > I have a suspicion that we are getting close to a philosophical > question <<snip>> I'd just say RH's remark is plain wrong. For example, the operations permitted by a Turing machine are well-defined (or illegal), but every computable function, unanticipated or not, can be expressed in that language. I'd say it's some ill-defined "human readability" that's better captured by less black-and-white, so to speak, languages. But expressiveness/computability/unanticipated-ness simply cannot be better captured by any language. Turing completeness is the end of the line with respect to that. -- John Forkosh ( mailto: j@f.com where j=john and f=forkosh )
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| From | Richard Heathfield <invalid@see.sig.invalid> |
|---|---|
| Date | 2014-12-17 07:22 +0000 |
| Message-ID | <taakw.136698$Su5.107248@fx03.am4> |
| In reply to | #54805 |
JohnF wrote: > Tim Rentsch <txr@alumni.caltech.edu> wrote: >> Richard Heathfield <invalid@see.sig.invalid> writes: >>> <<snip>> >>> A language in which every possible construct is either >>> well-defined or illegal makes it very difficult for programmers >>> to add kinds of functionality unanticipated by the language >>> designers. >> >> I have a suspicion that we are getting close to a philosophical >> question <<snip>> > > I'd just say RH's remark is plain wrong. For example, > the operations permitted by a Turing machine are well-defined > (or illegal), but every computable function, unanticipated or not, > can be expressed in that language. I have a device in my possession that measures the precise distance between itself and three fixed points in the room. Please show me a well-defined C program that can read the data from my device correctly. I will test your program and let you know whether it works. If you can do it, I agree that I'm wrong. If you can't, I shan't. > I'd say it's some ill-defined "human readability" that's better > captured by less black-and-white, so to speak, languages. > But expressiveness/computability/unanticipated-ness simply cannot > be better captured by any language. Turing completeness is the > end of the line with respect to that. No, there's even more to computing than Turing completeness. -- Richard Heathfield Email: rjh at cpax dot org dot uk "Usenet is a strange place" - dmr 29 July 1999 Sig line 4 vacant - apply within
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| From | Ben Bacarisse <ben.usenet@bsb.me.uk> |
|---|---|
| Date | 2014-12-17 11:56 +0000 |
| Message-ID | <87bnn232xd.fsf@bsb.me.uk> |
| In reply to | #54806 |
Richard Heathfield <invalid@see.sig.invalid> writes: > JohnF wrote: > >> Tim Rentsch <txr@alumni.caltech.edu> wrote: >>> Richard Heathfield <invalid@see.sig.invalid> writes: >>>> <<snip>> >>>> A language in which every possible construct is either >>>> well-defined or illegal makes it very difficult for programmers >>>> to add kinds of functionality unanticipated by the language >>>> designers. >>> >>> I have a suspicion that we are getting close to a philosophical >>> question <<snip>> >> >> I'd just say RH's remark is plain wrong. For example, >> the operations permitted by a Turing machine are well-defined >> (or illegal), but every computable function, unanticipated or not, >> can be expressed in that language. > > I have a device in my possession that measures the precise distance between > itself and three fixed points in the room. Please show me a well-defined C > program that can read the data from my device correctly. I will test your > program and let you know whether it works. If you can do it, I agree that > I'm wrong. If you can't, I shan't. This, I think, is at the heart of any apparent disagreement about terms like "powerful". You like C because it is powerful and easy to add functionality to, and you think that these properties originate in the fact C is, in some sense, less rigorously defined than some other languages (again, I don't think exactly what the means really matters to the argument). Can you give an example or two of real programming languages that do not have these properties, or have them to a much lesser extent than C does? Ideally they should ones which lack these properties because they are too "well-defined". That would give people like me some sort of baseline to know what you mean by these terms. <snip> -- Ben.
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| From | Malcolm McLean <malcolm.mclean5@btinternet.com> |
|---|---|
| Date | 2014-12-17 05:43 -0800 |
| Message-ID | <d3e0eb86-0219-4b23-be79-b271fbd0ad8b@googlegroups.com> |
| In reply to | #54832 |
On Wednesday, December 17, 2014 11:56:40 AM UTC, Ben Bacarisse wrote: > > Can you give an example or two of real programming languages that do not > have these properties, or have them to a much lesser extent than C does? > Ideally they should ones which lack these properties because they are > too "well-defined". That would give people like me some sort of > baseline to know what you mean by these terms. > An example would be trying to write low-level matrix operations in Java. Java has a well-defined interface for 2d arrays, effectively all are C double **s with a list of row sizes. So there's no difference between a ragged and rectangular array. It means that you can't index mtx[y][posterror] without triggering a runtime exception, which is good. However it also means that ,mtx[y-1][x] + mtx[y+1][x] is not terribly efficient, because you're taking values from widely different areas in memory, and doing binds checking you almost certainly don't need. C allows you to treat a 2D array as a 1D array, the problems disappear and it becomes mtx[i-width] + mtx[i+width];
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| From | Rosario193 <Rosario@invalid.invalid> |
|---|---|
| Date | 2014-12-18 18:30 +0100 |
| Message-ID | <9i369ahc8k6jbhvilivubd1uj4a7m9ehjt@4ax.com> |
| In reply to | #54838 |
On Wed, 17 Dec 2014 05:43:40 -0800 (PST), Malcolm McLean <malcolm.mclean5@btinternet.com> wrote: >On Wednesday, December 17, 2014 11:56:40 AM UTC, Ben Bacarisse wrote: >> >> Can you give an example or two of real programming languages that do not >> have these properties, or have them to a much lesser extent than C does? >> Ideally they should ones which lack these properties because they are >> too "well-defined". That would give people like me some sort of >> baseline to know what you mean by these terms. >> >An example would be trying to write low-level matrix operations in Java. > >Java has a well-defined interface for 2d arrays, effectively all are C >double **s with a list of row sizes. So there's no difference between a >ragged and rectangular array. >It means that you can't index mtx[y][posterror] without triggering a runtime >exception, which is good. >However it also means that >,mtx[y-1][x] + mtx[y+1][x] is not terribly efficient, because you're taking values >from widely different areas in memory, and doing binds checking you almost >certainly don't need. > >C allows you to treat a 2D array as a 1D array, the problems disappear and it >becomes >mtx[i-width] + mtx[i+width]; the above one can do without UB if each tipe is fixed know size and operation on them are defined ok example mtx is a pointe of 32 bit pointer linear to mem reserved that programmer know how many bits has i is a i32 widtd i32 etc and all operations on them are defined without UBs
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| From | Rosario193 <Rosario@invalid.invalid> |
|---|---|
| Date | 2014-12-18 18:41 +0100 |
| Message-ID | <3c469a9ri3n77f07ouu3iiq8fc1h2422ai@4ax.com> |
| In reply to | #54973 |
On Thu, 18 Dec 2014 18:30:01 +0100, Rosario193
<Rosario@invalid.invalid> wrote:
>the above one can do without UB if each tipe is fixed know size and
>operation on them are defined ok
>example
>mtx is a pointe of 32 bit pointer linear to mem reserved that
>programmer know how many bits has
^^^^^^
programmer know how many bites that memory has
>i is a i32 widtd i32 etc
>and all operations on them are defined without UBs
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| From | Richard Heathfield <invalid@see.sig.invalid> |
|---|---|
| Date | 2014-12-17 14:34 +0000 |
| Message-ID | <Gvgkw.108407$9b1.76311@fx05.am4> |
| In reply to | #54832 |
Ben Bacarisse wrote: > Richard Heathfield <invalid@see.sig.invalid> writes: > >> JohnF wrote: >> >>> Tim Rentsch <txr@alumni.caltech.edu> wrote: >>>> Richard Heathfield <invalid@see.sig.invalid> writes: >>>>> <<snip>> >>>>> A language in which every possible construct is either >>>>> well-defined or illegal makes it very difficult for programmers >>>>> to add kinds of functionality unanticipated by the language >>>>> designers. >>>> >>>> I have a suspicion that we are getting close to a philosophical >>>> question <<snip>> >>> >>> I'd just say RH's remark is plain wrong. For example, >>> the operations permitted by a Turing machine are well-defined >>> (or illegal), but every computable function, unanticipated or not, >>> can be expressed in that language. >> >> I have a device in my possession that measures the precise distance >> between itself and three fixed points in the room. Please show me a >> well-defined C program that can read the data from my device correctly. I >> will test your program and let you know whether it works. If you can do >> it, I agree that I'm wrong. If you can't, I shan't. > > This, I think, is at the heart of any apparent disagreement about terms > like "powerful". You like C because it is powerful and easy to add > functionality to, and you think that these properties originate in the > fact C is, in some sense, less rigorously defined than some other > languages (again, I don't think exactly what the means really matters to > the argument). Almost. I wasn't thinking of it in comparison to other languages, actually, but purely in its own terms. But yes, one of the reasons I like C is that it doesn't get in one's way when one knows what one is doing. (Of course, this does mean that, when one *doesn't* know what one is doing, one is in for trouble; but, if one can't take a joke, one shouldn't have joined.) > Can you give an example or two of real programming languages that do not > have these properties, or have them to a much lesser extent than C does? > Ideally they should ones which lack these properties because they are > too "well-defined". That would give people like me some sort of > baseline to know what you mean by these terms. I think Pascal is probably a good example. -- Richard Heathfield Email: rjh at cpax dot org dot uk "Usenet is a strange place" - dmr 29 July 1999 Sig line 4 vacant - apply within
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| From | Ben Bacarisse <ben.usenet@bsb.me.uk> |
|---|---|
| Date | 2014-12-18 02:15 +0000 |
| Message-ID | <87oar1zory.fsf@bsb.me.uk> |
| In reply to | #54842 |
Richard Heathfield <invalid@see.sig.invalid> writes: > Ben Bacarisse wrote: > >> Richard Heathfield <invalid@see.sig.invalid> writes: <snip> >>> I have a device in my possession that measures the precise distance >>> between itself and three fixed points in the room. Please show me a >>> well-defined C program that can read the data from my device correctly. I >>> will test your program and let you know whether it works. If you can do >>> it, I agree that I'm wrong. If you can't, I shan't. >> >> This, I think, is at the heart of any apparent disagreement about terms >> like "powerful". You like C because it is powerful and easy to add >> functionality to, and you think that these properties originate in the >> fact C is, in some sense, less rigorously defined than some other >> languages (again, I don't think exactly what the means really matters to >> the argument). > > Almost. I wasn't thinking of it in comparison to other languages, actually, > but purely in its own terms. Ah, we now be talking about different things. My comment relates to statements like this: | A language in which every possible construct is either well-defined or | illegal makes it very difficult for programmers to add kinds of | functionality unanticipated by the language designers. That seems to be contrasting C with other languages (even if hypothetical ones). > But yes, one of the reasons I like C is that it > doesn't get in one's way when one knows what one is doing. (Of course, this > does mean that, when one *doesn't* know what one is doing, one is in for > trouble; but, if one can't take a joke, one shouldn't have joined.) > >> Can you give an example or two of real programming languages that do not >> have these properties, or have them to a much lesser extent than C does? >> Ideally they should ones which lack these properties because they are >> too "well-defined". That would give people like me some sort of >> baseline to know what you mean by these terms. > > I think Pascal is probably a good example. Does the fact that ISO Pascal explicitly permits extensions later this answer? -- Ben.
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| From | James Kuyper <jameskuyper@verizon.net> |
|---|---|
| Date | 2014-12-17 22:31 -0500 |
| Message-ID | <m6thp7$mu7$2@dont-email.me> |
| In reply to | #54905 |
On 12/17/2014 09:15 PM, Ben Bacarisse wrote: ... > Does the fact that ISO Pascal explicitly permits extensions later this > answer? "later" => "alter"? -- James Kuyper
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| From | Ben Bacarisse <ben.usenet@bsb.me.uk> |
|---|---|
| Date | 2014-12-18 17:19 +0000 |
| Message-ID | <87ppbgyiyc.fsf@bsb.me.uk> |
| In reply to | #54907 |
James Kuyper <jameskuyper@verizon.net> writes: > On 12/17/2014 09:15 PM, Ben Bacarisse wrote: > ... >> Does the fact that ISO Pascal explicitly permits extensions later this >> answer? > > "later" => "alter"? Yes, thanks. -- Ben.
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| From | Richard Heathfield <invalid@see.sig.invalid> |
|---|---|
| Date | 2014-12-18 07:52 +0000 |
| Message-ID | <bJvkw.131011$td3.44933@fx34.am4> |
| In reply to | #54905 |
Ben Bacarisse wrote: > Richard Heathfield <invalid@see.sig.invalid> writes: > >> Ben Bacarisse wrote: >> >>> Richard Heathfield <invalid@see.sig.invalid> writes: > <snip> >>>> I have a device in my possession that measures the precise distance >>>> between itself and three fixed points in the room. Please show me a >>>> well-defined C program that can read the data from my device correctly. >>>> I will test your program and let you know whether it works. If you can >>>> do it, I agree that I'm wrong. If you can't, I shan't. >>> >>> This, I think, is at the heart of any apparent disagreement about terms >>> like "powerful". You like C because it is powerful and easy to add >>> functionality to, and you think that these properties originate in the >>> fact C is, in some sense, less rigorously defined than some other >>> languages (again, I don't think exactly what the means really matters to >>> the argument). >> >> Almost. I wasn't thinking of it in comparison to other languages, >> actually, but purely in its own terms. > > Ah, we now be talking about different things. My comment relates to > statements like this: > > | A language in which every possible construct is either well-defined or > | illegal makes it very difficult for programmers to add kinds of > | functionality unanticipated by the language designers. > > That seems to be contrasting C with other languages (even if > hypothetical ones). I'll hope you'll forgive me for being a pain, but if there was a comparison going on in my head at the time of writing it would have been a comparison between C-locked-down and C-free-to-be-cool. > >> But yes, one of the reasons I like C is that it >> doesn't get in one's way when one knows what one is doing. (Of course, >> this does mean that, when one *doesn't* know what one is doing, one is in >> for trouble; but, if one can't take a joke, one shouldn't have joined.) >> >>> Can you give an example or two of real programming languages that do not >>> have these properties, or have them to a much lesser extent than C does? >>> Ideally they should ones which lack these properties because they are >>> too "well-defined". That would give people like me some sort of >>> baseline to know what you mean by these terms. >> >> I think Pascal is probably a good example. > > Does the fact that ISO Pascal explicitly permits extensions later this > answer? It does? I didn't know. And does that answer your question? :-) -- Richard Heathfield Email: rjh at cpax dot org dot uk "Usenet is a strange place" - dmr 29 July 1999 Sig line 4 vacant - apply within
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