On 2015-03-30 04:57 PM, Aldo Davide wrote:
So basically, I think it would be useful for cabal to be able to support an arbitrary list of directories, e.g.:
/home/user/projects/foo/.cabal-sandbox/x86_64-linux-ghc-7.8.4-packages.conf.d /home/user/.ghc/x86_64-linux-7.8.4/package.conf.d /usr/lib64/ghc-7.8.4/package.conf.d
Whenever a package is needed, then it would look it up in all of those directories. If a new package is to be installed, it would be installed in the topmost directory. In other words, it would overlay these directories one on top of the other, with the topmost one being used for read-write and the other ones being read-only.
This has always been available. See my http://www.vex.net/~trebla/haskell/sicp.xhtml#sandbox In fact, read the whole thing.