{
  description = "Python spaghetti from samw";

  inputs = {
    treefmt-nix.url = "github:numtide/treefmt-nix";
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
  };

  outputs =
    {
      self,
      nixpkgs,
      treefmt-nix,
      ...
    }:
    let
      systems = [
        "aarch64-darwin"
        "x86_64-linux"
      ];
      eachSystem = f: nixpkgs.lib.genAttrs systems (system: f nixpkgs.legacyPackages.${system});
      treefmtEval = eachSystem (pkgs: treefmt-nix.lib.evalModule pkgs ./treefmt.nix);
    in
    {
      devShells = eachSystem (pkgs: {
        default = pkgs.mkShellNoCC {
          buildInputs = with pkgs; [
            uv
            ty
          ];
        };
      });
      formatter = eachSystem (pkgs: treefmtEval.${pkgs.stdenv.hostPlatform.system}.config.build.wrapper);
      # for `nix flake check`
      checks = eachSystem (pkgs: {
        formatting = treefmtEval.${pkgs.system}.config.build.check self;
      });
    };
}