Hew

// A chat session is an actor: state lives in fields and only its handlers
// can mutate it. Ordinary actor calls wait for the handler and return a
// Result, whether or not the handler itself returns a value.
actor Session {
    let user: string;
    var messages: Vec<string> = Vec.new();
    receive fn post(text: string) {
        messages.push(text);
    }
    receive fn count() -> i64 {
        messages.len()
    }
}
 
fn main() {
    let chat = spawn Session { user: "ada", messages: [] };
    chat.post("hello").expect("actor stopped");
    chat.post("world").expect("actor stopped");
    let total = chat.count();
    match total {
        .Ok(n) => println(f"{n} messages posted"),
        .Err(_) => println("session unavailable"),
    }
}