anchor.diff:  
     overlays = [ overlay ];
   
  -in
  -
  -let
  +  config  = { };
  +
      nixpkgs = import ./nixpkgs.nix;
      linuxPkgs = nixpkgs { inherit config overlays; system = "x86_64-linux" ; };
     darwinPkgs = nixpkgs { inherit config overlays; system = "x86_64-darwin"; };
  
positive.code: #     };);
  
  let
    nixpkgs = import ./nixpkgs.nix;
  
    config = {
      allowUnfree = true;
      # For parameterized-0.5.0.0, which we patch for compatbility with
      # proto3-wire-1.2.0 (which also uses the same patch)
      allowBroken = true;
    };
  
    overlay = pkgsNew: pkgsOld: {
  
      grpc = pkgsNew.callPackage ./nix/grpc.nix { };
  
      haskellPackages = pkgsOld.haskellPackages.override {
        overrides = haskellPackagesNew: haskellPackagesOld: rec {
  
          haskell-src =
            haskellPackagesNew.callHackage "haskell-src" "1.0.3.1" {};
  
negative.code:                 })
              );
  
  
        };
      };
  