> I do have GHC 6.10 still installed; but why does it not build > against the new GHC?
Because of a design decision Andres Loeh once made: try cat `which ghc`. You'll see that ghc finds the packages containing ghc libraries by iterating over $PATH. So the wrong ghc is found and their libraries are found. solutions: keep two different environments: env -i ghc_6_10_and_libs -p ~/ghc-6.10-env env -i ghc_6_12_and_libs -p ~/ghc-6.12-env or such. Then use either PATH=$PATH:~/ghc_6_10_and_libs/bin or PATH=$PATH:~/ghc_6_12_and_libs/bin A more complicated solution is using hack-nix which somewhat tries automating this for you. However I only patch packages to work with new ghcs. HTH Marc Weber _______________________________________________ nix-dev mailing list [email protected] https://mail.cs.uu.nl/mailman/listinfo/nix-dev
