Hi, Am Mittwoch, den 25.08.2010, 12:03 +1000 schrieb Ivan Lazar Miljenovic: > On 24 August 2010 21:18, Joachim Breitner <[email protected]> wrote: > > Am Dienstag, den 24.08.2010, 09:30 +0100 schrieb Magnus Therning: > >> On Tue, Aug 24, 2010 at 06:50, Mathew de Detrich <[email protected]> wrote: > >> > - in some situations doing a general update with arch (through clyde or > >> > packer) breaks ghc (last time it happened packer tried to > >> > uninstall/update > >> > arch packages which failed because those packages had dependencies. The > >> > files got removed but since unregister failed ghc thought they still > >> > existed) > >> > >> This is arguably an error in the Arch packages. The dependencies aren't > >> quite > >> as strict as they really should be. I've taken the approach of never > >> letting > >> pacman update any haskell-* package. Instead I do a small song-and-dance > >> where I first remove the packages in question, and any package that > >> depends on > >> them, then I re-install what I just removed. > > > > In Debian, this cannot happen any more, as libraries are tied to the > > packages of their dependencies via the ABI hash used by ghc. (If I am > > correctly understanding the symptoms). So using apt-get upgrade will > > never break any Debian-installed packages. > > Interesting; I've been discussing with Ciaran McCreesh on a > possibility of getting something like that into Paludis for use with > Exherbo (a few non-Haskell related things are starting to annoy me > with the petty politics, etc. of Gentoo and Exherbo has some really > nice ideas). How exactly do you do this? Register the ABI hash upon > installation and check if it ever changes? Or is this all done when > you build the package since Debian uses binary packages?
the latter. Build-Dependencies are unversioned or matching the Cabal range. At build time, the ABI of the library is used to construct the name of a „virtual package“ which is then Provide:’ed. For each dependency, the „virtual package“ containing the hash is depended upon. The code is at http://darcs.debian.org/pkg-haskell/haskell-devscripts/ and the (not particularly pretty) result can be seen at http://packages.debian.org/sid/libghc6-xmonad-contrib-dev > > OTOH, you cannot expect Debian to always and immediately install the > > latest Cabal versions – there are possibly good reasons for not > > upgrading. > > Yes, least of which is someone spending the time to notice that a > package is out of date and bothering to update it + test that update > (including any packages that depend upon it). ..and consider whether the update is an improvement and worth the trouble. New is not always better. Greetings, Joachim -- Joachim "nomeata" Breitner mail: [email protected] | ICQ# 74513189 | GPG-Key: 4743206C JID: [email protected] | http://www.joachim-breitner.de/ Debian Developer: [email protected]
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