[Haskell-cafe] Packages

Austin Seipp mad.one at gmail.com
Tue Sep 23 07:09:15 EDT 2008

Excerpts from Cetin Sert's message of Tue Sep 23 05:55:21 -0500 2008:
> Let's say I go and compile a library from sources and install it through
> Cabal.
> How can I update the binary version of the library Cabal installed after
> recompiling the library using newer/modified sources?

I'm not quite sure I understand the question - if you for example
install foo 0.1 using cabal, and then you want foo 0.2, you just
install it with the same procedures. In this case, the higher version
number means the other is 'shadowed' by it, and if you explicitly need
to use foo 0.1, you can either specify this as a constraint of the

> build-depends: foo == 0.1

in the package's .cabal file, or you will have to explicitly pass
ghc/ghci the flag:

> -hide-package foo-0.2

Otherwise, GHC will default to building anything that depends on foo
against the newest version.

OTOH, if you for example install foo 0.1 from stable sources, then
checkout the HEAD version which is also listed as v0.1 in the .cabal
file, reinstalling it will simply overwrite the old version entirely.

Does that answer your query?


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