[Haskell-cafe] A few questions on using Cabal

[Isaac Jones]

Niklas Broberg <niklas.broberg at gmail.com> writes:

> I've just started experimenting with the new Cabal system, and I must
> say it's really sweet. Thanks a lot to all involved!

Yay!

> After trying it on some simple tasks I have collected a few questions:
>
> * What about 'setup uninstall'? Surely there should be an automatic
> way of uninstalling packages and executables?

We'd like to do this eventually, but it doesn't work yet.  A lot of
people are using cabal as a layer under the OS package system (like in
Debian) so the package manager handles removing the package itself.

> * Is there some way to direct the installation of a package to an
> auxiliary package-conf file, i.e. separate from the 'global' and
> 'user' package databases?
> E.g. 'runhaskell Setup.hs register --package-conf=foo.conf' (doesn't work)

No way to do this yet either... patches welcome :) That should be a
pretty easy thing to add; a half hour for someone who knows how the
command-line parser works.

> * Is there some way to bundle several packages into a single
> installation unit? Similar to how you can specify several executables,
> or executables and a library package, I would want a way to say that a
> bundle will install several (possibly interrelated) packages at the
> same time.

Nope.  This is also on the todo list, but we're not sure how it'll
look yet.  We were calling such things "shipments" to distinguish them
from packages.

We wanted to get basic packages working first, and the next goal is to
get the package database (Hackage) online.  That's proceeding nicely,
thanks to Lemmih.

> * If I specify a library package and an executable in the same cabal
> bundle, where the executable uses the library, the files that make up
> the library get compiled twice. Once when setting up the package, and
> then again when compiling the executable. How come?

Beacuse this is a bit of a workaround.  Don't complain too much or I
think Ross will kick me.  The "right" way to do this is probably with
"shipments".

> That's all for now, possibly more to come later. =)

So the short answer is that there are still some things that make
cabal less convinient than it could be, but we've got them in mind,
and we're happy to accept patches to add them!


peace,

  isaac