[Nix-dev] haskell-ng / cabal-install problem

[Peter Simons]

Hi Tobias,

 > What I need is cabal 1.20.x because I would like to use ghc-mod which
 > is not compatible with 1.22.x because of a file format change in cabal
 > leading to ghc-mod being unable to parse.

We don't have cabal-install 1.20.x. There is cabal-install 1.18.x,
though, which is the latest version GHC 7.8.x can compile with its own
core libraries:

  $ nix-env -qaP -A haskell.packages.ghc784 cabal-install
  haskell.packages.ghc784.cabal-install_1_18_0_8  cabal-install-1.18.0.8
  haskell.packages.ghc784.cabal-install           cabal-install-1.22.3.0

Best regards,
Peter