I DON'T KNOW ANYTHING ABOUT RUST

lua_thing.rs

use mlua::Lua;
use mlua::Result;

fn main() -> Result<()> {
    println!("Hello, world!");

    let lua = Lua::new();

    {
        let mut rust_val = Vec::<i32>::new();

        lua.scope(|scope| {
            // We create a 'sketchy' Lua callback that holds a mutable reference to the variable
            // `rust_val`.  Outside of a `Lua::scope` call, this would not be allowed
            // because it could be unsafe.

            lua.globals().set(
                "sketchy",
                scope.create_function_mut(|_, ()| {
                    rust_val.insert(0, 1);
                    Ok(())
                })?,
            )?;

            lua.load("sketchy()").exec()
        })?;

        assert_eq!(rust_val, vec![1]);
    }

    Ok(())
}