haskell - Using cabal with multiple GHC versions

Question

I got both ghc6 and ghc7 on my desktop. To install new packages (for the specific ghc version), I use cabal with the flag --with-compiler=<ghc-dir> to specify for which ghc i want the package installed.

I do cabal update before installing any new package. But how to I specify for which ghc I want the update? I mean, there is no --with-compiler flag as with cabal install. I would think that just like I use ghc-pkg7 for ghc7, there would be cabal7. Apart from the cabal install command which I know to which ghc version it is applying, I don't know which ghc is affected with the other cabal commands.

Also, when I do ghc-pkg check I find problems with some packages and I don't know how to fix.

I would really like to know - if anyone does have - good practices when using multiple ghc versions on the same machine. e.g. how to proceed with installation, updates, etc.

Answer 1

You can create two configuration files, say ~/.cabal/config and ~/.cabal/config7, and use the un(der)documented option --config-file to select between the two.