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From: ludo@gnu.org (Ludovic =?utf-8?Q?Court=C3=A8s?=)
Subject: Re: Patches to implement system roll-back and switch-generation
Date: Wed, 19 Oct 2016 23:07:40 +0200
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In-Reply-To: <87inssx0y4.fsf@gmail.com> (Chris Marusich's message of "Sat, 15
	Oct 2016 23:28:03 -0700")
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To: Chris Marusich <cmmarusich@gmail.com>
Cc: guix-devel@gnu.org

Hi Chris,

Chris Marusich <cmmarusich@gmail.com> skribis:

> ludo@gnu.org (Ludovic Court=C3=A8s) writes:
>> We can now avoid monadic procedures by using the declarative counterpart
>> of the monadic API.  That is, we could write:
>>
>>   (define (grub-configuration-file =E2=80=A6)      ;normal proc
>>     (computed-file "grub.cfg" builder))
>>
>> instead of:
>>
>>   (define (grub-configuration-file =E2=80=A6)      ;monadic proc
>>     (gexp->derivation "grub.cfg" builder))
>>
>> I would welcome such changes.
>>
>
> That's an interesting idea.  However, in this case, I think we need to
> pass the build options (from the parsed command-line arguments) along
> somehow.  How should we set the build options when using the declarative
> 'computed-file' procedure?  It seems like the most obvious way would be
> to pass the build options in as arguments to the 'computed-file'
> procedure, but is there a better way?

Which build options?  There=E2=80=99s a direct correspondence between, say,
=E2=80=98gexp->derivation=E2=80=99 and =E2=80=98computed-file=E2=80=99 and =
the arguments are essentially
the same.  Unless I=E2=80=99m overlooking something (again!), the change I
suggest above is a mechanical change.

HTH,
Ludo=E2=80=99.