public class Metro
{
    4 => int beatsPerMeasure;
    140 => int beatsPerMinute;

    1 => int beat;
    1 => int measure;

    1 => int totalBeats;
    
    (1.0 / (beatsPerMinute * beatsPerMeasure / 4.0))::minute => dur beatLength;
    beatsPerMeasure::beatLength => dur measureLength;

    false => int running;
    
    Event pulse;

    fun void run()
    {
        while(running)
        {
            beatLength => now;

            1 +=> beat;
            1 +=> totalBeats;

            if(beat > beatsPerMeasure)
            {
                1 => beat;
                1 +=> measure;
            }
            
            pulse.broadcast();
        }
    }

    fun void start()
    {
        true => running;
        spork ~ run();
    }

    fun void stop()
    {
        false => running;
    }  
}