actor accumulator {
    state {
        total: u64 = 0
    }

    window total_view : (total)
        readers(observe)

    on Add(value: u64) {
        total = total + value
    }
}

leaf source {
    process {
        forward(accumulator, Add(10))
    }
}

leaf observe {
    reads accumulator.total_view
    process {
        read(accumulator.total_view.total)
        emit(total)
    }
}

pipeline main {
    source -> accumulator -> observe
}

core main {
    actors: [accumulator]
    leaves: [source, observe]
    pipelines: [main]
    steps: 3
}