This crate contains procedural macros to make creating Rhai plugin-modules much easier.

Export an Entire Rust Module to a Rhai Module

use rhai::{EvalAltResult, FLOAT};
use rhai::plugin::*;
use rhai::module_resolvers::*;

#[export_module]
mod advanced_math {
pub const MYSTIC_NUMBER: FLOAT = 42.0 as FLOAT;

pub fn euclidean_distance(x1: FLOAT, y1: FLOAT, x2: FLOAT, y2: FLOAT) -> FLOAT {
((y2 - y1).abs().powf(2.0) + (x2 -x1).abs().powf(2.0)).sqrt()
}
}

fn main() -> Result<(), Box<EvalAltResult>> {
let mut engine = Engine::new();
let m = rhai::exported_module!(advanced_math);
let mut r = StaticModuleResolver::new();
r.insert("Math::Advanced".to_string(), m);
engine.set_module_resolver(Some(r));

assert_eq!(engine.eval::<FLOAT>(
r#"import "Math::Advanced" as math;
let m = math::MYSTIC_NUMBER;
let x = math::euclidean_distance(0.0, 1.0, 0.0, m);
x"#)?, 41.0);
Ok(())
}

Register a Rust Function with a Rhai Module

use rhai::{EvalAltResult, FLOAT, Module, RegisterFn};
use rhai::plugin::*;
use rhai::module_resolvers::*;

#[export_fn]
fn distance_function(x1: FLOAT, y1: FLOAT, x2: FLOAT, y2: FLOAT) -> FLOAT {
((y2 - y1).abs().powf(2.0) + (x2 -x1).abs().powf(2.0)).sqrt()
}

fn main() -> Result<(), Box<EvalAltResult>> {

let mut engine = Engine::new();
engine.register_fn("get_mystic_number", || { 42 as FLOAT });
let mut m = Module::new();
rhai::set_exported_fn!(m, "euclidean_distance", distance_function);
let mut r = StaticModuleResolver::new();
r.insert("Math::Advanced".to_string(), m);
engine.set_module_resolver(Some(r));

assert_eq!(engine.eval::<FLOAT>(
r#"import "Math::Advanced" as math;
let m = get_mystic_number();
let x = math::euclidean_distance(0.0, 1.0, 0.0, m);
x"#)?, 41.0);
Ok(())
}

Register a Plugin Function with an Engine

use rhai::{EvalAltResult, FLOAT, Module, RegisterFn};
use rhai::plugin::*;
use rhai::module_resolvers::*;

#[rhai::export_fn]
pub fn distance_function(x1: FLOAT, y1: FLOAT, x2: FLOAT, y2: FLOAT) -> FLOAT {
((y2 - y1).abs().powf(2.0) + (x2 -x1).abs().powf(2.0)).sqrt()
}

fn main() -> Result<(), Box<EvalAltResult>> {

let mut engine = Engine::new();
engine.register_fn("get_mystic_number", || { 42 as FLOAT });
rhai::register_exported_fn!(engine, "euclidean_distance", distance_function);

assert_eq!(engine.eval::<FLOAT>(
r#"let m = get_mystic_number();
let x = euclidean_distance(0.0, 1.0, 0.0, m);
x"#)?, 41.0);
Ok(())
}