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

[Ivan Lazar Miljenovic]

On 23 November 2010 08:26, 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-1.0.9.1, HDBC-2.2.6.1 and
> HDBC-mysql-0.6.3 even though they are already installed (and work fine). Why
> does it do this?

1) Does "ghc-pkg check" complain about them?  If so, it will rebuild them.

2) Do you mean it rebuilds the same version or a different/older version?

3) Did you build those packages with any compile-time flags,
constraints, etc.?  If so, I believe cabal-install defaults to wanting
to rebuild them with the default settings.

I believe that if you want to stop cabal-install from rebuilding
non-broken packages, that unpacking what you want to install and then
running "cabal install" within that directory (as opposed to doing
"cabal install foo") is meant to work.

-- 
Ivan Lazar Miljenovic
Ivan.Miljenovic at gmail.com
IvanMiljenovic.wordpress.com