KRL for the home automation prototype (incoming call example)

rules.rb

rule incoming_call {
    select when phone incoming_call
    pre {
        media_state = get_media_state();
        new_media_state = (media_state eq "play") => "pause" | media_state;
        light_level = get_light_level();
        new_light_level = (light_level <= 8) => 8 | light_level;
    }
    {
        set_media_state(new_media_state);
        set_light_level(new_light_level);
    }
    fired {
        set app:prev_media_state media_state;
        set app:prev_light_level light_level;
    }
}

rule call_finished {
    select when phone hung_up
    {
        set_media_state(app:restore_media_state);
        set_light_level(app:prev_light_level);
    }
    fired {
        clear app:prev_media_state;
        clear app:prev_light_level;
    }
}