Core Concepts

Type Mapping

BridgeRust automatically converts between Rust types and their target language equivalents.

Rust Type	Python Type	Node.js Type	Notes
String	str	string	Copied on conversion
i32, f64, etc.	int, float	number
bool	bool	boolean
Vec<T>	List[T]	T[]	Converted recursively
Option<T>	Optional[T]	T | null	None becomes None/null
Result<T, E>	T (or raise)	T (or throw)	Err causes an exception
struct (exported)	class	class	Must be marked with #[export]

Async Support

BridgeRust has first-class support for async functions.

#[bridgerust::export]
pub async fn fetch_data(url: String) -> Result<String> {
    // Standard Rust async code
    let resp = reqwest::get(url).await?.text().await?;
    Ok(resp)
}

• Python: Returns an Awaitable (coroutine). Use await fetch_data(...) in Python.
• Node.js: Returns a Promise. Use await fetch_data(...) in JavaScript.

runtime requirement: For async functions to work, you generally need a runtime. BridgeRust assumes a Tokio runtime is available if you use async features.

Error Handling

Return Result<T, E> from your functions. If E implements ToString or Display, it will be converted into:

• Python: RuntimeError (or a custom exception if configured).
• Node.js: Error object (rejected Promise for async).

#[bridgerust::export]
pub fn divide(a: f64, b: f64) -> Result<f64, String> {
    if b == 0.0 {
        return Err("Cannot divide by zero".to_string());
    }
    Ok(a / b)
}