anchor.diff:  # Based on https://github.com/nmattia/homies/blob/master/default.nix
   let
   
  -  pkgs = pkgs-unstable;
  +  pkgs = pkgs-darwin;
   
  -  pkgs-unstable = import (builtins.fetchTarball {
  +  pkgs-darwin = import (builtins.fetchTarball {
       # Descriptive name to make the store path easier to identify
       name = "nixpkgs-19.09-darwin";
  -    # rev obtained with `git ls-remote https://github.com/nixos/nixpkgs-channels nixpkgs-unstable`
  +    # rev obtained with `git ls-remote https://github.com/nixos/nixpkgs-channels nixpkgs-darwin`
       url = "https://github.com/nixos/nixpkgs/archive/bb7c495f2e74bf49c32b14051c74b3847e1e2be0.tar.gz";
       # hash obtained with `nix-prefetch-url --unpack <url from above>`
       sha256 = "0dm57i9cpyi55h519vc6bc9dlcmxr3aa4pf9pkff6lnkrywi30nm";
  
positive.code: 
    hub = pkgs.gitAndTools.hub;
  
    lab = pkgs-unstable.gitAndTools.lab;
  
    custom = rec {
      inherit (pkgs) callPackage;
  
negative.code:       sha256 = "0h2kzdfiw43rbiiffpqq9lkhvdv8mgzz2w29pzrxgv8d39x67vr9";
      }) {};
  
      emacsHead = pkgs.emacs.overrideAttrs (oldAttrs: rec {
        name = "emacs-${version}";
        version = "27.0";
        srcRepo = true;
        src = pkgs.fetchFromGitHub {
          owner = "emacs-mirror";
          repo = "emacs";
          rev = "a76a1d0c0b5c63bbed4eeeb7aa87269621956559";
          sha256 = "0cx7ahk18amqlivmpxvq9d3a9axbj5ag6disssxkbn8y7bib0s0i";
        };
        patches = [];
      });
  
      vim = pkgs-darwin.callPackage ./vim {
        inherit metals yarn2nix;
        inherit (pkgs.vimUtils) buildVimPluginFrom2Nix;
      };
  