shared_counter.nula

// Shared Counter — distributed counter via actor messaging.
// Multiple worker actors increment a shared counter held by a
// coordinator. Demonstrates request-response patterns between
// actors using the `!` send operator and behavior dispatch.
//
// Run with: nulang examples/shared_counter.nula

actor Counter {
    state value: Int = 0

    behavior increment(amount: Int) {
        self.value = self.value + amount
    }

    behavior decrement(amount: Int) {
        self.value = self.value - amount
    }

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

actor Worker {
    state counter_ref: Int = 0
    state name: String = "anon"

    behavior init(name_str: String, counter: Int) {
        self.name = name_str
        self.counter_ref = counter
    }

    behavior do_inc(amount: Int) {
        self.counter_ref ! increment(amount)
    }

    behavior do_dec(amount: Int) {
        self.counter_ref ! decrement(amount)
    }
}

fn main() {
    let counter = spawn Counter {}

    let w1 = spawn Worker {}
    let w2 = spawn Worker {}

    w1 ! init("alice", counter)
    w2 ! init("bob", counter)

    w1 ! do_inc(10)
    w2 ! do_inc(5)
    w1 ! do_dec(3)

    counter ! read()

    w2 ! do_inc(42)
    counter ! read()

    0
}