08_actors.nula

// 08_actors.nula - Actors: spawn, send, and behaviors
// Demonstrates: actor declaration, state, behaviors, spawn,
//               message passing with !, actors printing from behaviors
//
// Run: nulang examples/08_actors.nula

// A counter actor that tracks and displays its count
actor Counter {
    state count: Int = 0

    behavior increment(by: Int) {
        self.count = self.count + by
    }

    behavior show() {
        perform IO.print("  Counter value: " + perform Int.to_string(self.count))
    }
}

// A greeter actor with configurable greeting and name
actor Greeter {
    state greeting: String = "Hello"
    state name: String = "World"

    behavior set_greeting(g: String) {
        self.greeting = g
    }

    behavior set_name(n: String) {
        self.name = n
    }

    behavior greet() {
        perform IO.print("  " + self.greeting + ", " + self.name + "!")
    }
}

// A calculator actor that prints results
actor Calculator {
    state last: Int = 0

    behavior add(x: Int, y: Int) {
        let result = x + y
        self.last = result
        perform IO.print("  " + perform Int.to_string(x) + " + " + perform Int.to_string(y) + " = " + perform Int.to_string(result))
    }

    behavior multiply(x: Int, y: Int) {
        let result = x * y
        self.last = result
        perform IO.print("  " + perform Int.to_string(x) + " * " + perform Int.to_string(y) + " = " + perform Int.to_string(result))
    }
}

fn main() {
    perform IO.print("Counter actor:")
    let counter = spawn Counter {}
    counter ! increment(5)
    counter ! increment(3)
    counter ! show()

    perform IO.print("Greeter actor:")
    let greeter = spawn Greeter {}
    greeter ! greet()
    greeter ! set_name("Actor System")
    greeter ! greet()

    perform IO.print("Calculator actor:")
    let calc = spawn Calculator {}
    calc ! add(40, 2)
    calc ! multiply(6, 7)

    0
}