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=<

Answer 1

Now (cabal version 1.24.0.0), one can

$ cabal install  -w path-to-ghc-executable-1 
$ cabal install  -w path-to-ghc-executable-2

to install packages separately for multiple different GHCs.

(The meta-variable path-to-ghc-executable-i can be, like, /usr/bin/ghc-7.10.3, /usr/local/bin/ghc-8.4.3 etc.)

How did I know? This command can be found via https://www.haskell.org/cabal/users-guide/installing-packages.html or cabal install --help.

The post-condition looks like this: I installed QuickCheck for ghc-8.0.1 and ghc-6.12.1, then ~/.cabal/lib looks like:

➜  lib pwd      
/home/lee/.cabal/lib
➜  lib tree -L 2
.
├── x86_64-linux-ghc-6.12.1
│   └── QuickCheck-2.8.2-GeOZQRSfeF7EtuZhBovRUq
└── x86_64-linux-ghc-8.0.1
    └── QuickCheck-2.9.2-AzbjWrJo3WFD60ZxKurQ3s