Re: John McCarthy died today.

From	Kaz Kylheku <kaz@kylheku.com>
Newsgroups	comp.lang.c
Subject	Re: John McCarthy died today.
Date	2011-11-05 01:55 +0000
Organization	A noiseless patient Spider
Message-ID	<20111104214808.434@kylheku.com> (permalink)
References	(3 earlier) <j90aoo$jom$1@news.albasani.net> <20111104115106.357@kylheku.com> <4EB40FC0.8090206@verizon.net> <20111104135545.861@kylheku.com> <j9216t$ss2$1@dont-email.me>

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On 2011-11-05, James Kuyper <jameskuyper@verizon.net> wrote:
> On 11/04/2011 01:58 PM, Kaz Kylheku wrote:
> ...
>> Which problem?
>> 
>> I'm thinking of  accidental assignments:
>> 
>>   if (defence_condition = UNDER_NUCLEAR_ATTACK)
>>     launch_full_counterstrike();
>> 
>> This problem is caused by the similarity of == and =, but, sure, it would also
>> go away if you couldn't have an assignment in that context.
>
> And my point is that's the superior solution. 

You have to make up your mind what the root cause is of the
=/== mixup bugs. Is it:

a) similarity between = and ==

b) expressions that can contain side effects?

If you say b, but then you redesign the language by only eliminating the plain
assignment operator from expressions, while continuing to allow expressions to
use operators like &= and ++, and to call functions that have side effects,
that is inconsistent with your point! You're then admitting that the side
effects are not really the root cause, just the assignment operator
specifically.

If you believe b) you can make an imperative language in which expressions are
purely functional: no side effects, and calls to pure functions only, not to
procedures.

But it remains that it's the similarity between = and == that leads to
the programming mistake.  The programmer did not make some mistake in
the destructive manipulation of data; he didn't even want the expression
to be destructive, but only misspelled the darn operator!

How will you protect the programmer from misspelling one non-destructive
operator for another in a pure expression?

What programming language butchery do you recommend for the situation
when - is written instead of +?

Thread

John McCarthy died today. Kaz Kylheku <kaz@kylheku.com> - 2011-10-25 00:44 +0000
  Re: John McCarthy died today. Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-10-25 01:27 -0700
  Re: John McCarthy died today. Kleuskes & Moos <kleuske@somewhere.else.net> - 2011-10-25 09:27 +0000
  Re: John McCarthy died today. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-10-25 11:27 +0100
  Re: John McCarthy died today. Ark <akhasin@macroexpressions.com> - 2011-10-29 13:33 -0400
    Re: John McCarthy died today. Willem <willem@toad.stack.nl> - 2011-10-29 17:51 +0000
      Re: John McCarthy died today. Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2011-10-29 21:28 +0300
      Re: John McCarthy died today. Keith Thompson <kst-u@mib.org> - 2011-10-29 11:57 -0700
        Re: John McCarthy died today. Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-10-30 08:20 -0700
      Re: John McCarthy died today. Ark <akhasin@macroexpressions.com> - 2011-11-04 05:20 -0400
        Re: John McCarthy died today. Kaz Kylheku <kaz@kylheku.com> - 2011-11-04 15:53 +0000
          Re: John McCarthy died today. James Kuyper <jameskuyper@verizon.net> - 2011-11-04 12:16 -0400
            Re: John McCarthy died today. Kaz Kylheku <kaz@kylheku.com> - 2011-11-04 17:58 +0000
              Re: John McCarthy died today. James Kuyper <jameskuyper@verizon.net> - 2011-11-04 20:49 -0400
                Re: John McCarthy died today. Kaz Kylheku <kaz@kylheku.com> - 2011-11-05 01:55 +0000
                Re: John McCarthy died today. "BartC" <bc@freeuk.com> - 2011-11-07 10:54 +0000
                Re: John McCarthy died today. "Charles Richmond" <netnews@aquaporin4.com> - 2011-11-07 07:36 -0600
                Re: John McCarthy died today. Kaz Kylheku <kaz@kylheku.com> - 2011-11-07 19:49 +0000
                Re: John McCarthy died today. James Kuyper <jameskuyper@verizon.net> - 2011-11-07 15:49 -0500
                Re: John McCarthy died today. Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-11-08 00:38 -0800
                Re: John McCarthy died today. James Kuyper <jameskuyper@verizon.net> - 2011-11-08 07:05 -0500
                Re: John McCarthy died today. lawrence.jones@siemens.com - 2011-11-08 09:12 -0500
                Re: John McCarthy died today. Kaz Kylheku <kaz@kylheku.com> - 2011-11-08 16:48 +0000
                Re: John McCarthy died today. James Kuyper <jameskuyper@verizon.net> - 2011-11-08 12:12 -0500
                Re: John McCarthy died today. Kaz Kylheku <kaz@kylheku.com> - 2011-11-08 23:27 +0000
                Re: John McCarthy died today. Keith Thompson <kst-u@mib.org> - 2011-11-08 14:10 -0800
                Re: John McCarthy died today. James Kuyper <jameskuyper@verizon.net> - 2011-11-08 17:16 -0500
                Re: John McCarthy died today. lawrence.jones@siemens.com - 2011-11-09 13:51 -0500
                Re: Looping Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2011-11-09 19:21 -0700
                Re: Looping Kaz Kylheku <kaz@kylheku.com> - 2011-11-10 02:34 +0000
                Re: John McCarthy died today. Joe Wright <joewwright@comcast.net> - 2011-11-08 17:49 -0500
                Re: John McCarthy died today. Keith Thompson <kst-u@mib.org> - 2011-11-08 16:35 -0800
                Re: John McCarthy died today. Joe Wright <joewwright@comcast.net> - 2011-11-09 01:08 -0500
                Re: John McCarthy died today. Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-11-09 01:26 -0800
                Re: John McCarthy died today. Joe Wright <joewwright@comcast.net> - 2011-11-09 08:18 -0500
                Re: John McCarthy died today. Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-11-09 05:32 -0800
                Re: John McCarthy died today. Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-11-09 01:24 -0800
                Re: John McCarthy died today. Quentin Carbonneaux <qcarbonn@invalid.com> - 2011-11-09 11:59 +0000
                Re: John McCarthy died today. Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-11-09 05:34 -0800
                Re: John McCarthy died today. Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2011-11-08 18:31 +0200
                Re: John McCarthy died today. Keith Thompson <kst-u@mib.org> - 2011-11-07 14:06 -0800
                Re: John McCarthy died today. "BartC" <bc@freeuk.com> - 2011-11-08 02:01 +0000
                Re: John McCarthy died today. Keith Thompson <kst-u@mib.org> - 2011-11-07 23:16 -0800
                Re: John McCarthy died today. Kaz Kylheku <kaz@kylheku.com> - 2011-11-08 05:18 +0000
                Re: John McCarthy died today. Keith Thompson <kst-u@mib.org> - 2011-11-07 23:17 -0800
                Re: John McCarthy died today. Malcolm McLean <malcolm.mclean5@btinternet.com> - 2011-11-08 01:46 -0800
                Re: John McCarthy died today. "BartC" <bc@freeuk.com> - 2011-11-08 13:02 +0000
                Re: John McCarthy died today. Keith Thompson <kst-u@mib.org> - 2011-11-08 14:19 -0800
                Re: John McCarthy died today. Edward Rutherford <edward.p.rutherford79@REMOVETHIS.gmail.com> - 2011-11-08 22:23 +0000
                Re: John McCarthy died today. James Kuyper <jameskuyper@verizon.net> - 2011-11-08 18:13 -0500
                Re: John McCarthy died today. Kaz Kylheku <kaz@kylheku.com> - 2011-11-08 23:38 +0000
                Re: John McCarthy died today. Kaz Kylheku <kaz@kylheku.com> - 2011-11-08 23:18 +0000
                Re: John McCarthy died today. Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2011-11-10 12:40 +0200
                Re: John McCarthy died today. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-11-10 11:39 +0000
                Re: John McCarthy died today. "BartC" <bc@freeuk.com> - 2011-11-10 12:23 +0000
                Re: John McCarthy died today. 88888 Dihedral <dihedral88888@googlemail.com> - 2011-11-10 05:38 -0800
                Re: John McCarthy died today. Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2011-11-10 17:29 +0200
                Re: John McCarthy died today. David Thompson <dave.thompson2@verizon.net> - 2011-11-21 02:39 -0500
                Re: John McCarthy died today. Keith Thompson <kst-u@mib.org> - 2011-11-08 16:34 -0800
                Re: John McCarthy died today. Malcolm McLean <malcolm.mclean5@btinternet.com> - 2011-11-09 01:37 -0800
                Re: John McCarthy died today. Keith Thompson <kst-u@mib.org> - 2011-11-09 13:25 -0800
                Re: John McCarthy died today. Ian Collins <ian-news@hotmail.com> - 2011-11-10 10:36 +1300
                Re: John McCarthy died today. Malcolm McLean <malcolm.mclean5@btinternet.com> - 2011-11-09 23:47 -0800
                Re: John McCarthy died today. Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-11-10 00:21 -0800
                Re: John McCarthy died today. Keith Thompson <kst-u@mib.org> - 2011-11-10 03:04 -0800
                Re: John McCarthy died today. gazelle@shell.xmission.com (Kenny McCormack) - 2011-11-10 15:20 +0000
                Re: John McCarthy died today. Jorgen Grahn <grahn+nntp@snipabacken.se> - 2011-11-12 23:22 +0000
                Re: John McCarthy died today. Kaz Kylheku <kaz@kylheku.com> - 2011-11-13 01:44 +0000
                Re: John McCarthy died today. "Charles Richmond" <netnews@aquaporin4.com> - 2011-11-13 04:18 -0600
                Re: John McCarthy died today. Kaz Kylheku <kaz@kylheku.com> - 2011-11-13 16:57 +0000
                Re: John McCarthy died today. Robert Wessel <robertwessel2@yahoo.com> - 2011-11-13 11:59 -0600
                Re: John McCarthy died today. gazelle@shell.xmission.com (Kenny McCormack) - 2011-11-13 18:54 +0000
                Re: John McCarthy died today. Keith Thompson <kst-u@mib.org> - 2011-11-13 14:47 -0800
                Re: John McCarthy died today. Kaz Kylheku <kaz@kylheku.com> - 2011-11-14 03:43 +0000
                Re: John McCarthy died today. Ike Naar <ike@sverige.freeshell.org> - 2011-11-14 09:00 +0000
                Re: John McCarthy died today. Kaz Kylheku <kaz@kylheku.com> - 2011-11-14 18:30 +0000
                Re: John McCarthy died today. James Kuyper <jameskuyper@verizon.net> - 2011-11-14 14:44 -0500
                Re: John McCarthy died today. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-11-14 20:13 +0000
                Re: John McCarthy died today. Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-11-14 00:21 -0800
                Re: John McCarthy died today. Lauri Alanko <la@iki.fi> - 2011-11-10 15:26 +0000
                Re: John McCarthy died today. Kaz Kylheku <kaz@kylheku.com> - 2011-11-10 01:51 +0000
                Re: John McCarthy died today. Edward Rutherford <edward.p.rutherford79@REMOVETHIS.gmail.com> - 2011-11-09 17:15 +0000
                Re: John McCarthy died today. "BartC" <bc@freeuk.com> - 2011-11-09 18:04 +0000
                Re: John McCarthy died today. Keith Thompson <kst-u@mib.org> - 2011-11-09 13:31 -0800
                Re: John McCarthy died today. Robert Wessel <robertwessel2@yahoo.com> - 2011-11-09 15:53 -0600
                Re: John McCarthy died today. "BartC" <bc@freeuk.com> - 2011-11-09 22:02 +0000
                Re: John McCarthy died today. Keith Thompson <kst-u@mib.org> - 2011-11-09 14:14 -0800
                Re: John McCarthy died today. Keith Thompson <kst-u@mib.org> - 2011-11-09 13:50 -0800
                Re: John McCarthy died today. James Kuyper <jameskuyper@verizon.net> - 2011-11-08 07:10 -0500
          Re: John McCarthy died today. Keith Thompson <kst-u@mib.org> - 2011-11-04 14:51 -0700

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