{
  description =
    "Small exercises to get you used to reading and writing Rust code";

  inputs = {
    flake-compat = {
      url = "github:edolstra/flake-compat";
      flake = false;
    };
    flake-utils.url = "github:numtide/flake-utils";
    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
  };

  outputs = { self, flake-utils, nixpkgs, ... }:
    flake-utils.lib.eachDefaultSystem (system:
      let
        pkgs = nixpkgs.legacyPackages.${system};

        cargoBuildInputs = with pkgs;
          lib.optionals stdenv.isDarwin
          [ darwin.apple_sdk.frameworks.CoreServices ];

        rustlings = pkgs.rustPlatform.buildRustPackage {
          name = "rustlings";
          version = "5.6.1";

          buildInputs = cargoBuildInputs;
          nativeBuildInputs = [ pkgs.git ];

          src = with pkgs.lib;
            cleanSourceWith {
              src = self;
              # a function that returns a bool determining if the path should be included in the cleaned source
              filter = path: type:
                let
                  # filename
                  baseName = builtins.baseNameOf (toString path);
                  # path from root directory
                  path' = builtins.replaceStrings [ "${self}/" ] [ "" ] path;
                  # checks if path is in the directory
                  inDirectory = directory: hasPrefix directory path';
                in inDirectory "src" || inDirectory "tests"
                || hasPrefix "Cargo" baseName || baseName == "info.toml";
            };

          cargoLock.lockFile = ./Cargo.lock;
        };
      in {
        devShell = pkgs.mkShell {
          RUST_SRC_PATH =
            "${pkgs.rust.packages.stable.rustPlatform.rustLibSrc}";

          buildInputs = with pkgs;
            [ cargo rustc rust-analyzer rustlings rustfmt clippy ]
            ++ cargoBuildInputs;
        };
        apps = let
          rustlings-app = {
            type = "app";
            program = "${rustlings}/bin/rustlings";
          };
        in {
          default = rustlings-app;
          rustlings = rustlings-app;
        };
        packages = {
          inherit rustlings;
          default = rustlings;
        };
      });
}