A further pitfall I just discovered: $ cabal install --dry cabal-install leksah-0.8.0.6 Resolving dependencies... cabal: cannot configure cabal-install-0.8.2. It requires Cabal ==1.8.* For the dependency on Cabal ==1.8.* there are these packages: Cabal-1.8.0.2, Cabal-1.8.0.4 and Cabal-1.8.0.6. However none of them are available. Cabal-1.8.0.2 was excluded because Cabal-1.6.0.3 was selected instead Cabal-1.8.0.2 was excluded because ghc-6.10.4 requires Cabal ==1.6.0.3 Cabal-1.8.0.4 was excluded because Cabal-1.6.0.3 was selected instead Cabal-1.8.0.4 was excluded because ghc-6.10.4 requires Cabal ==1.6.0.3 Cabal-1.8.0.6 was excluded because Cabal-1.6.0.3 was selected instead Cabal-1.8.0.6 was excluded because ghc-6.10.4 requires Cabal ==1.6.0.3 That's on ghc-6.10.4 with Cabal-1.8.0.6. However, trying to install cabal-install and leksah separately works quite well. Indeed, they are already installed, but since they are not tracked by ghc-pkg, cabal forgot that it installed them, and keeps forgetting that (as I just discovered). I believe the pitfall is that since cabal is trying to install both packages at once, it is trying to figure out dependencies for them together. The behavior might even be perfectly valid if there are interdependencies between the two packages, but that's not the case here; maybe cabal should not try to detect that the packages are not related and can be installed separately. Or maybe, it should just allow using two different versions of the same package, for packages which are not linked together. -- Paolo Giarrusso - Ph.D. Student http://www.informatik.uni-marburg.de/~pgiarrusso/