[Nix-dev] Picking a GHC version to use

[Richard Wallace]

Hello all,

I'm trying out nix for managing installed Haskell packages because I
heard it was really nifty.  I'm having a bit of a problem.  Probably
I'm just a bit confused about how nix works, but I've been through the
docs and couldn't find an answer to my question.

I've installed the haskell-platform and that was easy enough, just
`nix-evn -i haskell-haskell-platform-ghc7.4.2-2012.2.0.0`.

Then I went on to try installing some other haskell packages, and they
triggered an install of ghc 7.4.1 when I already have 7.4.2 installed
and want to use that.

I also tried using cabal2nix to install cabal-dev, but that failed
because it was looking for package versions of mtl and tar that
weren't installed.

Not sure what I'm doing wrong here.  Any help would be appreciated.

Thanks,
Rich