{
  inputs = {
    flake-utils.url = "github:numtide/flake-utils";
  };

  outputs = { self, nixpkgs, flake-utils, ... }:
    let
      inherit (builtins) listToAttrs mapAttrs;

      mkPackage = pkgs: name: pkgs.callPackage ./pkgs/${name}.nix { };
      mkApp = drv: flake-utils.lib.mkApp { inherit drv; };
      mkOverlay = name:
        final: prev:
          final.setAttrByPath [ name ] (mkPackage name prev);

      allPackageNames = [ "d2" "d2_unstable" ];
      mkAllPackages = pkgs':
        listToAttrs
          (map
            (name: { inherit name; value = mkPackage pkgs' name; })
            allPackageNames);
    in
    {
      overlays = (listToAttrs
        (map
          (name: { inherit name; value = mkOverlay name; })
          allPackageNames
        )
      ) // {
        all = final: prev: mkAllPackages prev;
      };
    }
    // flake-utils.lib.eachDefaultSystem (system:
      let
        pkgs = import nixpkgs { inherit system; };
        packages = mkAllPackages pkgs;
      in
      {
        check = packages;

        inherit packages;
        apps = mapAttrs (name: mkApp) packages;
      });
}