anchor.diff:          buildInputs = haskellTools spec ++ myHaskellPackages spec;
       };
   
  -    ghcEnv_g42 = ghcEnv {
  +    ghcEnv_742 = ghcEnv {
           name = "ghc742";
           ghc = ghc.ghc742;
           hsPkgs = haskellPackages_ghc742;
  
positive.code:             lens
          ];
  
      };
  }
  
negative.code: pkgs :
  {
    allowUnfree = true;
    allowBroken = true;
    packageOverrides = self: with self; rec {
  
      haskellTools = spec: ([
  