From mboxrd@z Thu Jan  1 00:00:00 1970
From: Federico Beffa <beffa@ieee.org>
Subject: Re: reproducibility
Date: Wed, 13 Jan 2016 09:13:25 +0100
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To: =?UTF-8?Q?Ludovic_Court=C3=A8s?= <ludo@gnu.org>
Cc: Guix-devel <guix-devel@gnu.org>

On Tue, Jan 12, 2016 at 10:37 PM, Ludovic Court=C3=A8s <ludo@gnu.org> wrote=
:
> Federico Beffa <beffa@ieee.org> skribis:
>
>> On Sun, Jan 10, 2016 at 9:49 PM, Ludovic Court=C3=A8s <ludo@gnu.org> wro=
te:
>>> Federico Beffa <beffa@ieee.org> skribis:
>>>
>>>> I've noticed that a derivation is a function of the order of the
>>>> inputs. As an example, the following two input orders give rise to two
>>>> distinct derivations:
>>>>
>>>> A)
>>>>
>>>>     (inputs
>>>>      `(("texlive" ,texlive)
>>>>        ("texinfo" ,texinfo)
>>>>        ("m4" ,m4)
>>>>        ("libx11" ,libx11))
>>>>
>>>> B)
>>>>     (inputs
>>>>      `(("texinfo" ,texinfo)
>>>>        ("texlive" ,texlive)
>>>>        ("m4" ,m4)
>>>>        ("libx11" ,libx11))
>>>>
>>>> Is this intentional?
>>>
>>> Yes.  There are several places where order matters, most importantly
>>> search paths, and these are computed from the input lists.
>>
>> If order matters, it would probably be more robust to force internally
>> a specific order rather than relying on the (often random) order
>> defined in a package recipe (possibly created by an importer, ...).
>
> Most of the time any order would work, but I can imagine situations
> where the packager could purposefully choose a specific order.  So I=E2=
=80=99d
> rather not do any automatic sorting, if that=E2=80=99s what you have in m=
ind.

Just out of curiosity, could you provide a concrete example where the
order is purposefully specified.

Thanks,
Fede