[Nix-dev] GNU Guix 0.1 released (alpha)

[Ludovic Courtès]

Hi,

Florian Friesdorf <flo at chaoflow.net> skribis:

> Ludovic Courtès <ludo at gnu.org> writes:
>> Florian Friesdorf <flo at chaoflow.net> skribis:
>>> What are your thoughts on generating nix expressions from guix
>>> expressions for the purpose of package definition?
>>
>> Do you mean the opposite–generating Guix expressions from Nix?
>
> I actually meant guix -> nix, as guix being within a full language, I
> had gut feeling this direction might be preferable, see also below.

I think conversion has the same problem in both directions: simple
meta-data is trivially converted, but anything beyond that, especially
builder-side code, can hardly be automatically converted.

>> Marc Weber <marco-oweber at gmx.de> skribis:
>>>   - in which way you're going to utilize the new "power" of scheme first
>>>     applying to what problems?
>>
>> On the build side, it nicely replaces Bash, and also Coreutils,
>> Findutils, sed, and cURL.  :-)
>
> Do you have ideas how these replacements could be used if generating nix
> expressions from guix expressions?

It’s going to be hard to automate anything.  For instance, something like

  (substitute* (find-files "." "^Makefile$")
    (("/bin/sh")
     (which "sh")))

would have to be converted to

  find . -name Makefile -exec sed -i {} -e"s|/bin/sh|`which sh`|”

Not to mention code that adds, removes, or modifies the standard build
phases....

>> It reuses the daemon, and thus libstore, as described in ‘README’.
>
> I take that nix and guix nicely cooperatively use "/nix/store/" though
> it's rather unlikely that the two would actually create the same output.

Yes (I use it on top of NixOS currently.)

> Would it be feasible to depend on nixpkgs from within guix packages?

Yes, I did that in the beginning: you basically inject derivation paths
as returned by ‘nix-instantiate’ into the derivations that Guix produces.

> Would it be feasible to do it the other way round?

In theory yes, because ‘import’ in the Nix language can import .drv
files–a little-known feature.  ;-)

In practice, though, it can only do that if the .drv defines an
environment variable called ‘name’, which Guix derivations don’t
normally do.  (This is an example of how arguments to derivations are
sometimes abused as arguments to the ‘derivation’ primitive.)

Thanks,
Ludo’.