Re: Implementation dependent behaviour (WAS: Re: Programming language and IDE design)

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From	Ivan Godard <ivan@ootbcomp.com>
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Subject	Re: Implementation dependent behaviour (WAS: Re: Programming language and IDE design)
Date	Fri, 10 Jan 2014 09:11:04 -0800
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On 1/8/2014 10:21 AM, Kaz Kylheku wrote:
> On 2014-01-08, Ivan Godard <ivan@ootbcomp.com> wrote:
>> On 11/20/2013 2:29 AM, Martin Ward wrote:
>>
>> <snip>
>>
>>> (2) CPU designers may choose to implement that behaviour in hardware
>>> on the next iteration of the CPU. Now the programs run fast on *all*
>>> CPUs.
>>>
>>> Everybody wins.
>>
>> I am such a CPU designer. We faced the "undefined" issue in our Mill
>> family of general-purpose CPUs (ootbcomp.com). Not only are languages
>> under-constraining, they are also sometimes over-constraining: signed
>> integer overflow is undefined in C but required to wrap in Java.
>
> It's only undefined on paper. In reality, if you don't make it wrap in C like
> in Java, unknown numbers of C programs will break, and not all of them doing it
> by accident.

Or one may say that unknown numbers of C programs are already broken.

And the reality is that the program cannot even in practice depend on
wrapping; see http://www.airs.com/blog/archives/120, or just Google
"signed integer overflow in C".

Thread

Implementation dependent behaviour (WAS: Re: Programming language and IDE design) Martin Ward <martin@gkc.org.uk> - 2013-11-20 10:29 +0000
  Re: Implementation dependent behaviour (WAS: Re: Programming language and IDE design) Joshua Cranmer 🐧 <Pidgeot18@verizon.net> - 2013-11-23 01:06 -0600
    Re: Implementation dependent behaviour (WAS: Re: Programming language and IDE design) glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2013-11-24 21:51 +0000
    Re: Implementation dependent behaviour (WAS: Re: Programming language and IDE design) Martin Ward <martin@gkc.org.uk> - 2014-01-06 19:23 +0000
  Re: Implementation dependent behaviour (WAS: Re: Programming language and IDE design) Kaz Kylheku <kaz@kylheku.com> - 2013-12-17 23:07 +0000
    Re: Implementation dependent behaviour (WAS: Re: Programming language and IDE design) Martin Ward <martin@gkc.org.uk> - 2014-01-06 19:32 +0000
  Re: Implementation dependent behaviour (WAS: Re: Programming language and IDE design) Ivan Godard <ivan@ootbcomp.com> - 2014-01-08 09:02 -0800
    Re: Implementation dependent behaviour (WAS: Re: Programming language and IDE design) Kaz Kylheku <kaz@kylheku.com> - 2014-01-08 18:21 +0000
      Re: Implementation dependent behaviour (WAS: Re: Programming language and IDE design) Ivan Godard <ivan@ootbcomp.com> - 2014-01-10 09:11 -0800
      Re: Implementation dependent behaviour (WAS: Re: Programming language and IDE design) glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-01-10 23:08 +0000
        Re: Implementation dependent behaviour (WAS: Re: Programming language and IDE design) Ivan Godard <ivan@ootbcomp.com> - 2014-01-13 12:47 -0800
        Re: Implementation dependent behaviour (WAS: Re: Programming language and IDE design) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2014-01-14 14:16 +0000

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