Quick Start

Hello World

Start the REPL:

cargo run -- --repl

nulang> perform IO.print("Hello, Nulang!")
Hello, Nulang!

Or evaluate from the command line:

cargo run -- --eval 'perform IO.print("Hello, Nulang!")'

Variables and Functions

let x = 42
let y = x + 8

fn greet(name: String) -> String {
    "Hello, " + name
}

perform IO.print(greet("World"))

Records and Pattern Matching

type Person = { name: String, age: Int }

fn describe(p: Person) -> String {
    match p {
        { name, age } if age < 18 => name + " is young",
        { name, age } => name + " is " + Int.to_string(age)
    }
}

let alice = { name: "Alice", age: 30 }
perform IO.print(describe(alice))

Actors — The Heart of Nulang

actor Counter {
    state count: Int = 0

    behavior inc() {
        self.count = self.count + 1
    }

    behavior get(sender: Actor) {
        send sender reply(self.count)
    }
}

actor Main {
    behavior run() {
        let counter = spawn Counter {} in {
            send counter inc()
            send counter inc()
            send counter get(self)
        }
    }

    behavior reply(value: Int) {
        perform IO.print("Count is: " + Int.to_string(value))
    }
}

spawn Main {} in {}

Algebraic Effects

effect Logger {
    op log(msg: String) -> Unit
}

fn greet_with_log(name: String) {
    perform Logger.log("Greeting " + name)
    perform IO.print("Hello, " + name)
}

handle greet_with_log("World") {
    | Logger.log(msg) => {
        perform IO.print("[LOG] " + msg);
        resume(())
    }
}

Next

• Dive into Syntax Basics
• Explore the Type System
• Learn about Algebraic Effects
• Build Distributed Actors