use rhai::{Engine, EvalAltResult, RegisterFn, INT}; fn add(x: INT, y: INT) -> INT { x + y } fn main() -> Result<(), Box<EvalAltResult>> { let mut engine = Engine::new(); engine.register_fn("add", add); let result = engine.eval::<INT>("add(40, 2)")?; println!("Answer: {}", result); // prints 42 Ok(()) }