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rhai 0.16.1

Embedded scripting for Rust
Documentation

Rhai - embedded scripting for Rust

Rhai is a tiny, simple and very fast embedded scripting language for Rust that gives you a safe and easy way to add scripting to your applications. It provides a familiar syntax based on JavaScript and Rust and a simple Rust interface. Here is a quick example.

First, the contents of my_script.rhai:

// Brute force factorial function
fn factorial(x) {
if x == 1 { return 1; }
x * factorial(x - 1)
}

// Calling an external function 'compute'
compute(factorial(10))

And the Rust part:

use rhai::{Engine, EvalAltResult, RegisterFn};

fn main() -> Result<(), Box<EvalAltResult>>
{
// Define external function
fn compute_something(x: i64) -> bool {
(x % 40) == 0
}

// Create scripting engine
let mut engine = Engine::new();

// Register external function as 'compute'
engine.register_fn("compute", compute_something);

#   #[cfg(not(feature = "no_std"))]
#   #[cfg(not(target_arch = "wasm32"))]
assert_eq!(
// Evaluate the script, expects a 'bool' return
engine.eval_file::<bool>("my_script.rhai".into())?,
true
);

Ok(())
}

Optional features

Feature Description
unchecked Exclude arithmetic checking (such as overflows and division by zero). Beware that a bad script may panic the entire system!
no_function Disable script-defined functions if not needed.
no_module Disable loading external modules if not needed.
no_index Disable arrays and indexing features if not needed.
no_object Disable support for custom types and objects.
no_float Disable floating-point numbers and math if not needed.
no_optimize Disable the script optimizer.
only_i32 Set the system integer type to i32 and disable all other integer types. INT is set to i32.
only_i64 Set the system integer type to i64 and disable all other integer types. INT is set to i64.
no_std Build for no-std. Notice that additional dependencies will be pulled in to replace std features.
sync Restrict all values types to those that are Send + Sync. Under this feature, Engine, Scope and [AST] are all Send + Sync.
internals Expose internal data structures (beware they may be volatile from version to version).

See The Rhai Book for details on the Rhai script engine and language.