From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: Avoiding side effects
Date: Wed, 8 Oct 2008 09:35:43 +0200
Date: 2008-10-08T09:35:38+02:00 [thread overview]
Message-ID: <yhahjb0plj33$.1dx04ocsti32m$.dlg@40tude.net> (raw)
In-Reply-To: u1vyrbra1.fsf@no.email.thanks.invalid
On Wed, 08 Oct 2008 05:16:22 GMT, Anders Wirzenius wrote:
> "(see below)" <yaldnif.w@blueyonder.co.uk> writes:
>
>> On 07/10/2008 15:47, in article uprmc4g3i.fsf@no.email.thanks.invalid,
>> "Anders Wirzenius" <anders@no.email.thanks.invalid> wrote:
>>
>>> "(see below)" <yaldnif.w@blueyonder.co.uk> writes:
>>>
>>>> On 07/10/2008 12:08, in article wvbrfxn8hdc7.fsf@sun.com, "Ole-Hjalmar
>>>> Kristensen" <ole-hjalmar.kristensen@substitute_employer_here.com> wrote:
>>>>
>>>>> Yes, I think any program which use a read/write interface to a file
>>>>> will have side effects in that sense. The only way I can think of for
>>>>> avoiding this would be to mmap the whole file, then it will appear as
>>>>> an array of bytes.
>>>>
>>>> Why would stepping through an array not be thought a "side" effect?
>>>
>>> A function that returns the row of that array and only that
>>> would perhaps be a function without side effects. The information
>>> in that row can be fetched when needed.
>>
>> A function that always returns the same row of an array would be of little
>> use, I should think.
>
> I have a feeling that the function can be programmed so that it returns
> different row (numbers, or pointers in that array) depending on
> the content of the rows in that array ;-)
... which (content) cannot itself be a function, when mutable. There is no
way out of "functional singularity." (:-))
Even a pure function is not a function in the promoted sense. It is a
subroutine with one dedicated out parameter, called "result," such that all
effect of execution is limited to that parameter.
--
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de
next prev parent reply other threads:[~2008-10-08 7:35 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-09-30 5:50 Avoiding side effects Anders Wirzenius
2008-09-30 7:48 ` Jean-Pierre Rosen
2008-09-30 9:20 ` Anders Wirzenius
2008-09-30 11:36 ` Jean-Pierre Rosen
2008-09-30 12:43 ` Anders Wirzenius
2008-09-30 10:42 ` Ludovic Brenta
2008-09-30 11:12 ` Anders Wirzenius
2008-10-02 12:56 ` Ole-Hjalmar Kristensen
2008-10-06 12:09 ` Anders Wirzenius
2008-10-07 11:08 ` Ole-Hjalmar Kristensen
2008-10-07 14:24 ` (see below)
2008-10-07 14:47 ` Anders Wirzenius
2008-10-07 14:51 ` (see below)
2008-10-08 5:16 ` Anders Wirzenius
2008-10-08 7:35 ` Dmitry A. Kazakov [this message]
2008-10-08 15:32 ` (see below)
2008-10-13 12:27 ` Anders Wirzenius
2008-10-13 13:21 ` Marco
2008-10-13 18:55 ` (see below)
2008-10-14 7:30 ` Dmitry A. Kazakov
2008-10-14 11:44 ` Colin Paul Gloster
2008-10-13 18:49 ` (see below)
2008-10-13 21:22 ` Adam Beneschan
2008-10-13 21:53 ` (see below)
2008-10-14 6:17 ` mockturtle
2008-10-14 14:58 ` Adam Beneschan
2008-10-14 6:22 ` Avoiding side effects and other dogma Anders Wirzenius
2008-10-14 13:48 ` (see below)
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