{ lib, ... }:
rec
{
  nohash = s: builtins.substring 1 7 s;

  slice-hex = hex: { r = builtins.substring 0 2 hex; g = builtins.substring 2 2 hex; b = builtins.substring 4 5 hex; };

  # https://github.com/bertof/nix-rice
  rune-to-num = c:
    let
      k = lib.strings.toUpper c;
      dict = {
        "0" = 0;
        "1" = 1;
        "2" = 2;
        "3" = 3;
        "4" = 4;
        "5" = 5;
        "6" = 6;
        "7" = 7;
        "8" = 8;
        "9" = 9;
        "A" = 10;
        "B" = 11;
        "C" = 12;
        "D" = 13;
        "E" = 14;
        "F" = 15;
      };
    in
    assert(builtins.hasAttr k dict);
    builtins.getAttr k dict;

  drune-to-255 = hex: (rune-to-num (builtins.substring 0 1 hex)) * 15 + (rune-to-num (builtins.substring 1 2 hex));

  hex-to-rgb-comma-string = hex: let color = (slice-hex (nohash hex)); in "${builtins.toString (drune-to-255 color.r)},${builtins.toString (drune-to-255 color.g)},${builtins.toString (drune-to-255 color.b)}";

  num-to-rune = n:
    let
      ns = builtins.toString n;
      dict = {
        "0" = "0";
        "1" = "1";
        "2" = "2";
        "3" = "3";
        "4" = "4";
        "5" = "5";
        "6" = "6";
        "7" = "7";
        "8" = "8";
        "9" = "9";
        "10" = "A";
        "11" = "B";
        "12" = "C";
        "13" = "D";
        "14" = "E";
        "15" = "F";
      };
    in
    assert(builtins.hasAttr ns dict);
    builtins.getAttr ns dict;

  float-to-drune = f: "${num-to-rune (builtins.floor((255*f) / 16))}${num-to-rune (builtins.floor(255*f) - (builtins.floor((255 * f) / 16) * 16))}";
}