[Haskell-cafe] Re: Why cabal forces reinstallation of happstack-utils?

[Daniel Fischer]

On Wednesday 05 May 2010 01:45:29, Maciej Piechotka wrote:
>
> I updated local copy, as shown, but cabal wants to rebuild it anyway. My
> question was rather why the repo is considered at all when the package
> is installed.
>
> Regards

Okay, I didn't quite understand your question, sorry.
So, what's the situation?
You unpacked happstack-util, edited the cabal file to allow parsec-3.1, 
cd'ed to the unpacked directory and ran cabal install there, so you had 
happstack-util installed.
Then you ran cabal install --dry-run and it said
Resolving dependencies...
cabal: cannot configure happstack-util-0.5.0.

Is that correct?

I don't know why cabal does that.
As a guess: it looks at the .cabal file in the package index to find out 
what's needed, compares with the output of ghc-pkg list, finds a missing 
dependency (parsec-2.*) and decides to reinstall.