[arch-haskell] Cblrepo and dependencies

[Magnus Therning]

On 24 April 2015 at 13:52, SP <sp at orbitalfox.com> wrote:
> On 24/04/15 12:41, Magnus Therning wrote:
>> ~~~
>> % sudo pacman -Rncs ghc
>> % sudo pacman -S
>> haskell-{unixutils,aeson,ansi-wl-pprint,mtl,optparse-applicative,safe,stringsearch,tar,utf8-string,zlib}
>> % ./Setup.hs configure
>> % ./Setup.hs build
>> ~~~
>
> Good, on my way to doing that too, that isn't the problem. Clearly I
> somehow managed to mess the local repository here. As I said it happens
> a lot because of some networking/security related issues with this machine.
>
> But the question is, what happens is someone
> (unnecessarily/accidentally) manages to reinstall ghc? Is the whole set
> of haskell-* packages then unusable? Cause that seemed to be the effect
> it had on me.
>
> This is the issue I was trying to discuss here. Can you see what happens
> if you reinstall ghc?

Ah :)

If I re-install ghc all information about installed packages is lost,
on the ghc-level, and when I try to re-install e.g.
`haskell-unixutils` I get the same kind of error you were seeing.  The
root cause is that we use a mix of package management, `pacman` keeps
track of distro-level packages, and `ghc-pkg` keeps track of the ghc
level.  When re-installing ghc these two databases aren't in sync
anymore and using `pacman` to install results in errors on the
`ghc-pkg` level.  Basically, `pacman` won't re-install all
dependencies, since they are already installed, but when registering
with `ghc-pkg` it has no records of those dependencies.

/M

-- 
Magnus Therning                      OpenPGP: 0xAB4DFBA4
email: magnus at therning.org   jabber: magnus at therning.org
twitter: magthe               http://therning.org/magnus