> It would be nice to install README, COPYING, and LICENSE if they exist.
> It’s okay to not do that as a first step though.

I don't see the utility in installing these files. But, if we're not
doing them in this initial font-build-system, I suppose we can debate
later.

> Nitpick: the “build:” prefix in subject line is meant to refer to the
> configure/Makefile machinery of Guix itself.  I would use
>
>   build-system: Add 'font-build-system'.

Done!

>> +  (and (not target)                               ;XXX: no cross-compilation
>> +       (bag
>> +         (name name)
>> +         (system system)
>> +         (host-inputs `(,@(if source
>> +                              `(("source" ,source))
>> +                              '())
>> +                        ,@inputs
>> +
>> +                        ;; Keep the standard inputs of 'gnu-build-system'.
>> +                        ,@(standard-packages)))
>> +         (build-inputs native-inputs)
>> +         (outputs outputs)
>> +         (build font-build)
>> +         (arguments (strip-keyword-arguments private-keywords arguments)))))
>
> I would remove (and (not target) …).  After all, we know that the result
> is architecture-independent data, so we can build it natively regardless
> of whether TARGET is true.

Done!

> Also, (standard-packages) is way more than needed (it includes the whole
> toolchain, etc.; see build-system/gnu.scm).  Here all we need is tar,
> gzip, bzip2, and xz.

I have attempted something for this. I'm not sure I did it the correct
way. Do let me know.

I actually have very little understanding of what's going on in
guix/build-system/font.scm. I just copied guix/build-system/emacs.scm
and modified it a little. Can I find documentation of `bag' fields
somewhere in the manual?

> Could you updated it accordingly?
>
>> +(define* (install #:key outputs #:allow-other-keys)
>> +  "Install the package contents."
>> +  (let* ((out (assoc-ref outputs "out"))
>> +         (src-dir (getcwd))
>> +         (fonts-dir (string-append out "/share/fonts")))
>
> I’d avoid abbreviations in identifiers.  So “source” or
> “source-directory”, etc.

Done!

A side issue: I feel that the `install-file' procedure should print out
what it's doing to stdout (or some log port). Something like:

(format #t "~a -> ~a~%" source destination)

This would save us the trouble of implementing this log printing
everywhere `install-file' is called. For example, this could be very
useful in the 'install' phase of the font-build-sytem. WDYT?

> One last thing: could you add an entry for ‘font-build-system’ in
> guix.texi under “Build Systems”?

I have added a short description. Is it too short? Should I elaborate?

>> From d5a745fddf7b6512e4b5c317c19dc8cd3f9a8efe Mon Sep 17 00:00:00 2001
>> From: Arun Isaac <arunisaac@systemreboot.net>
>> Date: Mon, 15 May 2017 20:16:04 +0530
>> Subject: [PATCH 2/5] gnu: font-inconsolata: Use 'font-build-system'.
>>
>> * gnu/packages/fonts.scm (font-inconsolata): Switch to 'font-build-system'.
>
> [...]
>
>> From e0af4ce17f0e99f72926f93b5d5ed99df57cf06a Mon Sep 17 00:00:00 2001
>> From: Arun Isaac <arunisaac@systemreboot.net>
>> Date: Mon, 15 May 2017 20:18:08 +0530
>> Subject: [PATCH 3/5] gnu: font-ubuntu: Use 'font-build-system'.
>>
>> * gnu/packages/fonts.scm (font-ubuntu): Switch to 'font-build-system'.
>
> [...]
>
>> From c557da3c5167de0cb5714c5f545b07ac8cd55dae Mon Sep 17 00:00:00 2001
>> From: Arun Isaac <arunisaac@systemreboot.net>
>> Date: Mon, 15 May 2017 20:19:33 +0530
>> Subject: [PATCH 4/5] gnu: font-dejavu: Use 'font-build-system'.
>>
>> * gnu/packages/fonts.scm (font-dejavu): Switch to 'font-build-system'.
>
> [...]
>
>> From f302764eb627726548a89438b8c3b6a8ff5988d4 Mon Sep 17 00:00:00 2001
>> From: Arun Isaac <arunisaac@systemreboot.net>
>> Date: Mon, 15 May 2017 20:20:26 +0530
>> Subject: [PATCH 5/5] gnu: font-bitstream-vera: Use 'font-build-system'.
>>
>> * gnu/packages/fonts.scm (font-bitstream-vera): Switch to 'font-build-system'.
>> ---
>>  gnu/packages/fonts.scm | 33 +--------------------------------
>>  1 file changed, 1 insertion(+), 32 deletions(-)
>
> Really pleasant to see all these deletions.  :-)

Many more sweet deletions will follow once the font-build-system is
complete! :-)

The patches migrating the font packages to the font-build-system are not
properly complete. I'll send them in after more work. For now, please
find attached the patch for the font-build-system alone.