Quick Start

Hello World

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Run a one-liner:

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

Hello, Nulang!

Or start the REPL for an interactive session:

cargo run -- --repl

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: n, age: a } if a < 18 => n + " is young",
        { name: n, age: a } => n + " is " + perform Int.to_string(a)
    }
}

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() { self.count }
}

let c = spawn Counter {} in {
    ask c inc()
    ask c inc()
    ask c get()
}

Use spawn to create an actor, ask to call a behavior and wait for its return value, and send to fire-and-forget a message (useful in the full runtime where actors process messages concurrently).

Algebraic Effects

effect Logger {
    log: (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) resume => {
        perform IO.print("[LOG] " + msg)
    }
}

Next

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