ABS

module Demo;

interface Counter {
    Unit increment();
    Int getValue();
}

class CounterImpl implements Counter {
    Int value = 0;

    Unit increment() {
        value = value + 1;
    }

    Int getValue() {
        return value;
    }
}

interface Worker {
    Unit doWork(Counter c, Int times);
}

class WorkerImpl implements Worker {
    Unit doWork(Counter c, Int times) {
        Int i = 0;
        while (i < times) {
            c!increment();
            i = i + 1;
        }
    }
}

{
    Counter c = new CounterImpl();
    Worker w1 = new WorkerImpl();
    Worker w2 = new WorkerImpl();

    Fut<Unit> f1 = w1!doWork(c, 5);
    Fut<Unit> f2 = w2!doWork(c, 5);

    f1.get;
    f2.get;

    Fut<Int> fv = c!getValue();
    Int result = fv.get;
    println("Counter value: " ++ toString(result));
}