{
  description = "A naersk based rust flake";

  inputs = {
    utils.url = "github:numtide/flake-utils";
    naersk = {
      url = "github:nix-community/naersk";
      inputs.nixpkgs.follows = "nixpkgs";
    };
    index = {
      flake = false;
      url = "github:rust-lang/crates.io-index";
    };
  };

  outputs = { self, nixpkgs, utils, naersk, index }:
    let
      crate = self.lib.crate "bat";
      pname = crate.latest.name;
      forPkgs = pkgs:
        rec {
        # # `nix build`
        # packages.${pname} = crate.latest.package { inherit pkgs; };

        # # `nix run`
        # apps.${pname} = utils.lib.mkApp {
        #   drv = packages.${pname};
        # };
        # defaultApp = apps.${pname};
        };
      forSystem = system: forPkgs nixpkgs.legacyPackages."${system}";
    in
    (utils.lib.eachDefaultSystem forSystem) // {
      lib = rec {
        config = builtins.fromJSON (builtins.readFile "${index}/config.json");
        crate = name:
          let
            dbg = val: builtins.trace val val;
            strlen = builtins.stringLength;
            substr = builtins.substring;
            path = if strlen name < 4 then "${toString (strlen name)}/${substr 0 1 name}/${name}" else "${substr 0 2 name}/${substr 2 2 name}/${name}";
            build = meta: extra @ { pkgs, ... }:
              let naersk-lib = naersk.lib."${pkgs.system}"; in
              naersk-lib.buildPackage ((builtins.removeAttrs extra [ "pkgs" ]) // {
                root = pkgs.runCommandLocal "unpack-${name}" {} ''
                  mkdir -p $out
                  tar xzvf ${meta.tarball} -C $out --strip-components=1
                '';
              });
            versions = builtins.foldl'
              (p: i:
                let meta = i // rec { url = "${config.dl}/${name}/${i.vers}/download"; package = build meta; tarball = builtins.fetchurl { inherit url; sha256 = i.cksum; }; }; in
                p // { latest = meta; "${i.vers}" = meta; }
              )
              { }
              (map builtins.fromJSON (builtins.filter (s: builtins.isString s && strlen s > 0) (builtins.split "\n" (builtins.readFile "${index}/${path}"))));
          in
          versions;
      };
    };

}