[arch-haskell] Hackage support in bauerbill & follow-up on cabal2arch

[Xyne]

Hi,

I've added preliminary support for Hackage to Bauerbill. The following
now work:

"bauerbill -S --hackage [pkgs]" : build [pkgs] directly from Hackage*
"bauerbill -Si --hackage [pkgs]" : look up information about [pkgs]
"bauerbill -Ss --hackage [args]" : search for [args]
"bauerbill -Qu --hackage" : list upgradable Hackage packages

* with dependency resolution and build dependency tracking and removal

I've only run a few simple tests so far and I haven't announced this on
my site or on the forum yet. I'm waiting because I still have some
issues with cabal2arch which I hope can be solved before I push ahead
(see below, although I suppose what follows mostly concerns Don).

Btw, for now at least, if you enable AUR support as well (--aur) then
AUR packages take precedence over Hackage packages. The reasoning is
that AUR packages are more likely to be consistent as they're managed
by arch-haskell and thus have some human oversight. This may change
later if it's deemed move useful to give precedence to Hackage when
both are enabled.

Feedback and bug reports are always welcome.




Don,

I've updated to the latest version of cabal2arch and I've noticed that
most of the clutter is gone. I appreciate the changes and consider
them to be a great improvement, but it still creates an archive of the
build directory which I neither need nor want.

I would like to make the following suggestions:

*) add an option to create the archive of the build directory and
suppress it by default so that cabal2arch only create the build dir
with the PKGBUILD and install file when run with no options

*) add an option to create the PKGBUILD and install file in the current
working directory, and create nothing else

*) enable batching of multiple cabal files, so that it can accept
multiple URLs and paths on the command line (including paths to
directories which contain multiple cabal files)



I've also noticed that it downloads source files from Hackage. Is that
just to get the checksums for the archive? If so, it seems rather
wasteful. Would it not be possible to provide that information in the
cabal file or via a web API on Hackage?

If it is not possible to create the PKGBUILD without the source
archive, please add an option to first check if the source archive
exists in the build directory and mirror it if it doesn't. This would
prevent redundant downloads when building packages (which saves time
and bandwidth for all involved). Bauerbill in particular would benefit
from this by being able to handle the downloads itself (e.g. in
parallel). It could also preserve them between build sessions and
mirror them to only update when necessary.



Apropos the availability of information from Hackage, the Hackage
backend of Bauerbill currently uses the log and pkg-list.html
(in /packages/archives/) to create a plain-text database of all packages
on Hackage. You can view the "database" file created by bauerbill
(/tmp/bauerbill/hackage/hackage_db by default). This file is smaller
than both the log and pkg-list.html and follows the line format
<name> <version> <category> <type>: <synopsis>

Would it be possible to generate this file directly on Hackage? Again,
this would save bandwidth and it would also enable control over the
versions built by Bauerbill. Currently it tracks the latest versions by
simple parsing of the log. If the database file were instead provided
then it would use whichever versions it contained. This would make it
possible to specify which versions should be built. I don't know if
this would be an issue but version compatibility does seem to come up
quite often.

Of course even if it isn't an issue, it would still be beneficial to
provide such a plain-text file which applications such as Bauerbill
could use.



One final niggle: cabal2arch doesn't understand relative paths to
parent directories, e.g. "../cabal/foo.cabal".





Sorry for the long message with several suggestions/requests. I hope
they're considered reasonable and not too difficult to implement. I
would particularly appreciate the option to use local source files to
avoid redundant downloads and the option to suppress creation of the
build dir archive. Many thanks if you can do this.


Regards,
Xyne

p.s. Would it be useful to be able to rebuild all Hackage packages with
a simple command? If cabal2arch placed Hackage packages in a group, I
could easily add a "--rebuild-group" option to Bauerbill. I'm asking
because I don't actually know if this would be useful