proposal for ghc-pkg to use a directory of .conf files

[Sven Panne]

Duncan Coutts wrote:
> [...] The advantage of doing this is that it makes things easier for the
> package managers. Each individual file can belong to the appropriate
> package and so instead of having to execute registration/unregistration
> actions on install/uninstall it's just another file to add/remove. The
> other advantage is that there is no longer a global file that needs to
> be modified which means uninstallation is cleaner (most package managers
> do not remove files that were modified after installation).

These are exactly the reasons why e.g. the configuration files for apache2
on my SuSE Linux 9.1 are set up this way. It's very handy, clean and modular.

> [...] I had a peak at the code in ghc for dealing with .conf files. I'd guess
> it'd be best ok just check if the specified package file is a directory
> or an ordinary file and act accordingly. Ie you could say "-package-conf
> packages/" and ghc could by default read from $HC-LIB/package.conf and
> $HC-LIB/package.conf.d/ or something.

Sounds resaonable to me. I can't see any downsides of doing it this way.

> I can knock up a proof of concept patch if anyone thinks this is a good
> idea. It should be totally backward compatible, it's ok to use both, but
> ditro packagers might like to enforce a policy of using a directory of
> package files for external libraries.

OK, just send us a patch and if there are no objections we can merge it into
the HEAD.

Cheers,
    S.