xmonad.nix

    nixpkgs.overlays = [
    (_self: super: {
      haskellPackages = super.haskellPackages.override {
        overrides = self: hsuper: rec {
          taffybar = unstable.haskell.lib.overrideCabal unstable.haskellPackages.taffybar {
            patches = [
              (pkgs.fetchpatch {
              url = "https://raw.githubusercontent.com/spencerjanssen/dotfiles/master/nixos/taffybar-gi-gdkpixbuf-2.0.18.patch";
              sha256 = "00fczqii26z005dmzmn6zjbi4l7r0p0vsrs5v170sw556aic4vbh";
              })
            ];
          };
        };
      };
    })
    ];