[Haskell-cafe] Why does cabal unnecessarily reinstall dependencies?

Erik Hesselink hesselink at gmail.com
Tue Nov 23 05:57:12 EST 2010

It might be that it both your own package and the dependencies cabal
tries to reinstall all depend on some package P. If the dependencies
are installed depending on P version 1, but to satisfy all
dependencies for your own package, cabal needs them to depend on P
version 2, cabal will reinstall them (possibly breaking other packages
that depend on them; is this a bug?)

You can see if this is the case by running 'cabal install --dry-run -v'.


On Mon, Nov 22, 2010 at 22:26, Martijn van Steenbergen
<martijn at van.steenbergen.nl> wrote:
> Hello cafe,
> When I want to locally install my own package through "cabal install" it
> tries to reinstall dependencies convertible-, HDBC- and
> HDBC-mysql-0.6.3 even though they are already installed (and work fine). Why
> does it do this?
> cabal-install version 0.8.2
> using version of the Cabal library
> Mac OS Leopard
> Thanks,
> Martijn.
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