# fondant > an experimental, macro-only, boilerplate free, configuration management library ### example ```rust #[derive(Config, Default, Serialize, Deserialize)] #[filename = "config"] // ~/.config/appconfig/config.toml (XDG spec) #[extension = "toml"] // possible values: yaml, toml, json struct AppConfig { version: u8, path: String, } fn main() { let mut config = AppConfig::load().unwrap(); config.version = 3; config.path = "/home/np".to_string(); config.store(); } ```