{ pkgs, lib, stdenv, ... }: { palette, wallpaper, }: let strPal = let inherit (lib) concatStringsSep; inherit (builtins) foldl' attrValues; in concatStringsSep " " ( foldl' (acc: el: acc ++ (attrValues el)) [ ] [ palette.normal palette.bright palette.util ] ); in stdenv.mkDerivation { name = "generated-wallpaper.png"; src = wallpaper; buildInputs = [ pkgs.lutgen ]; phases = [ "installPhase" ]; installPhase = '' echo -e "Generating wallpaper from ${wallpaper} using palette:\n${strPal}.." ${lib.getExe pkgs.lutgen} apply --lum 0.8 -l 10 -s 128 -n 8 -o $out ${wallpaper} -- ${strPal} ''; }