> Yes please, that would be better.

I apologize for the delay.  What do you think about the attached patch?

I noticed that 'guile-gnome' has two 'doc-url' fields.  How can I handle
this?  (I ignored it for now.)

Also, is there a better way to create 'gnu-package-descriptor'?  Note
that I don't want to use setters.

For example, it should be possible to match a list of regexps against a
list of fields.  But I haven't found a way to do so because some fields
are optional and I also don't want to rely on their order.

> This code is run by the user’s Guile, which may be older than 2.0.7
> (‘http-get*’ was introduced in 2.0.7), so you can’t rely on it.

> What you can do is something along the lines of what (guix build
> download) does, but always return a port.  Maybe there’s a way to share
> code.

But how can I return a port with 'http-get'?  ('http-fetch*' is a
temporary function.)

> I’d rather change ‘group-packages’ to ‘read-package-fields’ or something
> like that.

I changed it to 'group-package-fields' and added some comments.

> identity

(identity sublst) won't work.

If (regexp-exec package-line-rx (first sublst)) returns #t,
'and=>' will call 'identity' with the result of 'regexp-exec'.  But it
should return 'sublst' instead.

I also changed 'gnu-package?'.  Please test.