Register a Generic Rust Function

No monomorphization

Due to its dynamic nature, Rhai cannot monomorphize generic functions automatically.

Monomorphization of generic functions must be performed manually.

Rust generic functions can be used in Rhai, but separate instances for each concrete type must be registered separately.

This essentially overloads the function with different parameter types as Rhai does not natively support generics but Rhai does support function overloading.

The example below shows how to register multiple functions (or, in this case, multiple overloaded versions of the same function) under the same name.

use std::fmt::Display;

use rhai::Engine;

fn show_it<T: Display>(x: &mut T) {
    println!("put up a good show: {x}!");

let mut engine = Engine::new();

engine.register_fn("print", show_it::<i64>)
      .register_fn("print", show_it::<bool>)
      .register_fn("print", show_it::<ImmutableString>);