anchor.diff:          (hself.callCabal2nix "xmonad"
             (git-ignore-nix.lib.gitignoreSource ./.) { });
         };
  -    overlay = fromHOL hoverlay;
  +    overlay = fromHOL hoverlay { };
       overlays = [ overlay ];
     in flake-utils.lib.eachDefaultSystem (system:
     let pkgs = import nixpkgs { inherit system overlays; };
  
positive.code:       packages = p: [ p.xmonad ];
      };
      defaultPackage = pkgs.haskellPackages.xmonad;
    }) // { inherit overlay overlays; lib = { inherit fromHOL; }; };
  }
  
negative.code:   };
    outputs = { self, flake-utils, nixpkgs, unstable, git-ignore-nix }:
    let
      hpath = { prefix ? null, compiler ? null }:
        (if prefix == null then [] else [ prefix ]) ++
        (if compiler == null
         then [ "haskellPackages" ]
         else [ "haskell" "packages" compiler ]
        );
      fromHOL = hol: comp: final: prev: with prev.lib; with attrsets;
        setAttrByPath (hpath comp)
          ((getAttrFromPath (hpath comp) prev).override (old: {
            overrides = composeExtensions (old.overrides or (_: _: {}))
              (hol final prev);
          }));
  