anchor.diff:                        sha256 = "06cjx9b8igmz9dh5zqfnpxy4ycq2wgbrayg9jnwvj1a08qbkzgd8";
                       };});
   
  -  pkgs = import <nixpkgs> {};
  +  # The main plugin, built with overridden package set
     plugin =
       onlyBuildHaskellPackages.callPackage ./default.nix {};
  -  ghc = onlyBuildHaskellPackages.ghcWithPackages (ps: [plugin]);
   
  +  # Overrides
     onlyBuildHaskellPackages = pkgs.haskell.packages.ghc802.override {
        overrides = self: super: {
          mkDerivation = args: super.mkDerivation (args // {
  
positive.code:         };
  
        };
  in
    pkgs.stdenv.mkDerivation {
      buildInputs = [ ghc kythe];
  
negative.code: let
    pkgs = import <nixpkgs> {};
  
    # kythe 2.6
    kythe = pkgs.callPackage ./simple-kythe.nix {};
  
    # Overloaded GHC version
    ghcWithVersion = pkgs.haskell.compiler.ghcHEAD.override { version = "8.3.20170726"; };
  
    ghcVersion = pkgs.stdenv.lib.overrideDerivation ghcWithVersion (oldAttrs : {
  