Re: Package variation

[Chris Marusich]

Hi Brett,

Brett Gilio <address@hidden> writes:

> (define-public gnome-custom
>   (package (inherit gnome)
>     (name "gnome-custom")
>     (inputs (alist-delete "nautilus" (package-inputs gnome)))))

The spirit of this is correct, but the implementation isn't quite
right.  The gnome package has no inputs:

  scheme@(guile-user)> ,use (gnu packages gnome)
  scheme@(guile-user)> ,use (guix packages)
  scheme@(guile-user)> (package-inputs gnome)
  $1 = ()

Instead, it has many propagated inputs.  So, you should probably write:

  (define-public gnome-custom
    (package (inherit gnome)
      (name "gnome-custom")
      (propagated-inputs (alist-delete
                           "nautilus"
                           (package-propagated-inputs gnome)))))

This will work as you expect.  It's not incorrect to use alist-delete
here, but FYI you can also use matching to do this as follows:

  (define-public gnome-custom
    (package (inherit gnome)
      (name "gnome-custom")
      (propagated-inputs (remove
                           (match-lambda
                             ;; Ignore the second value.
                             ((name _)
                              (string=? name "nautilus")))
                           (package-propagated-inputs gnome)))))

Whether or not you like that better probably depends on whether or not
you view the value returned by (package-propagated-inputs gnome) as an
alist or a list of 2-element lists.

> (services (cons* (service gnome-desktop-service-type
>                           config =>
>                           (gnome-desktop-configuration
>                            (inherit config)
>                            (gnome-package gnome-custom)))
>                  %desktop-services))

It looks like you're using "config =>" from the modify-services syntax
without actually using modify-services.  Try this instead:

  (services (cons* (service gnome-desktop-service-type
                            (gnome-desktop-configuration
                              (inherit config)
                              (gnome-package gnome-custom)))
                   %desktop-services))

This should create and add a gnome-desktop-service-type service instance
with the configuration you've specified.

Hope that helps!

-- 
Chris

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