What can Rust do for my Node.js? 

Software Engineer at Tuenti MadRust co-organizer  jrvidal  _rvidal 

Beware of Greeks Rustaceans bearing gifts 

Systems programming You know, like C/C++ 

Why coming here to talk/hear about Rust? 

Moving the needle 

Show me the money Native Extensions WebAssembly Async I/O Reinventing the wheel Node.js 

fn main() { println!("Hello Javascripters"); } But first... 

Rust is... 1. Typed fn my_middleware(req: Request) -> Response; 2. Compiled, and... $ rustc hello_world.rs && ./hello_world Hello, world! 3. ... compiled natively $ rustc hello_world.rs --target=aarch64-apple-ios && ./hello_world # good luck 

const http = require("http"); const hostname = "127.0.0.1"; const port = 8000; const server = http.createServer((req, res) => { res.statusCode = 200; res.end("Hello World\n"); }); server.listen(port, hostname, () => { console.log( `Listening at http://${hostname}:${port}/` ); }); Node.js — Getting Started 

extern crate tiny_http; use tiny_http::{Server, Response}; fn main() { let addr = "127.0.0.1:8000"; let server = Server::http(&addr) .unwrap(); println!("Listening at {}", addr); for request in server.incoming_requests() { let response = Response::from_string("Hello World\n"); request.respond(response); } } 

We want it all Frankie Cordoba 

We want it all Memory safety without Garbage collection Abstraction without Overhead Stability without Stagnation Hack without Fear 

Memory safety without Garbage collection and Speed fn main() { let some_number : &u32 = get_me_a_number(); println!("The number is {}", some_number); } fn get_me_a_number() -> &u32 { let numbers = vec![1, 2, 3]; &numbers[2] } 

Memory safety without Garbage collection and Speed fn main() { let some_number : &u32 = get_me_a_number(); println!("The number is {}", some_number); } fn get_me_a_number() -> &u32 { let numbers = vec![1, 2, 3]; // ⚠ ERROR &numbers[2] //^^^^^^^ borrowed value // does not live long enough } 

Server::new(|req| { let user_id = req.params.user_id; user_collection .find(|u| u.id == user_id) .map(|u| Response::from(u)) .or_else(|| Response::not_found()) }) .listen(&addr); Abstraction without Overhead and Speed 

Stability without Stagnation $ cargo new nodejsmad Created binary (application) `nodejsmad` project $ cd nodejsmad $ cargo add num_cpus Adding num_cpus v1.8.0 to dependencies $ cargo run Updating registry `https://github.com/rust-lang/crates.io-index` Compiling libc v0.2.43 Compiling num_cpus v1.8.0 Compiling nodejsmad v0.1.0 Finished dev [unoptimized + debuginfo] target(s) in 8.54s Running `target/debug/nodejsmad` Hello, world! 

Native Extensions Chan Walrus 

Native Extensions [...] the method for implementing Addons is rather complicated, involving knowledge of several components [...] Node.js docs/api/addons.html 

Native Extensions [...] the method for implementing Addons is rather complicated, involving knowledge of several components [...] Node.js docs/api/addons.html npm install -g neon-cli 

Getting started with Neon #[macro_use] extern crate neon; use neon::prelude::*; fn hello(mut cx: FunctionContext) -> JsResult { Ok(cx.string("hello node")) } register_module!(mut cx, { cx.export_function("hello", hello) }); ~ ~ ~ ~ ~ ~ ~ ~ ~ "native/src/lib.rs" 12L, 219C 00:00 

Advanced: native BigInts Watch for: num = "0.2" is all the required "business logic". JS classes are defined through macros: declare_types!( class JsBigInt for BigInt { init(cx) { /* ... */ } method toIntString(cx) { /* ... */ } } ) See: BigInts with Neon and num 

WebAssembly Rubendene (CC BY-SA 4.0) 

const binary = fs.readFileSync("./program.wasm"); const { instance } = await WebAssembly.instantiate(binary); instance.exports.expensiveComputation(); (module (export "expensiveComputation" (func $f)) (func $f (result i32) i32.const 1)) WebAssembly 

Getting started with wasm-pack extern crate cfg_if; extern crate wasm_bindgen; mod utils; use wasm_bindgen::prelude::*; #[wasm_bindgen] extern { #[wasm_bindgen(js_namespace=console)] fn log(s: &str); } #[wasm_bindgen] pub fn greet() { log("Hello, madridwasm!"); } ~ ~ ~ ~ 00:00 

Advanced: Exif metadata parser Watch for: Again, business logic contained in kamadak-exif = "0.3" More complex types crossing the Rust/Wasm-JS boundary: #[wasm_bindgen] pub fn get_exif(source: &[u8]) -> Vec Throwing from Rust/Wasm to JS: wasm_bindgen::throw_str(&format!("{:?}", error)) > pkg.get_exif([]) Error: InvalidFormat("Broken JPEG file") See: Exif parsing with Rust + Wasm 

Reinventing Node.js Christo Anestev 

Mode.js (ModeJsMadrid) /source % cargo run Compiling modejs v0.1.0 (file:///source) Finished dev [unoptimized + debuginfo] target(s) in 3.26s Running `target/debug/modejs` > 1 1 > var x = {foo: 2} undefined > x 00:00 

Async I/O Tamorlan (CC-BY-3.0) 

Everybody ends up in (callback) hell let ping_4ever = loop_fn(Client::new(), |client| { client.send_ping() .and_then(|client| client.receive_pong()) .and_then(|(client, done)| { if done { Ok(Loop::Break(client)) } else { Ok(Loop::Continue(client)) } }) }); 

#[async] fn fetch( client: Client ) -> IoResult { let response = await!(client.get(URL))?; if !response.status().is_success() { return Err( IoError::new(IoErrorKind::Other, FAIL_MSG) ); } let body = await!(response.body().concat())?; let string = String::from_utf8(body)?; Ok(string) } 

Where to go from here? https://www.rust-lang.org/documentation.html "The Book" Rust by Example https://www.meetup.com/MadRust/ Reddit, users forum WebAssembly: Rust and WebAssembly WG (check the !) wasm-pack (check the !) wasm-bindgen (check the !) Native addons, Neon: neon-bindings Web development, async I/O Are we web yet? Network Services WG We love "newbies" 

Keep Node-ing Thanks!