type InputResult {
  Parsed(value: Decimal)
  error Invalid
}

type State {
  total: Decimal
  factor: Decimal
}

type Sample {
  elapsed_ns: Int
  checksum: Text
}

parsed(value: Decimal) (result: Decimal) { result = value }
parsed(value: null) (result: Decimal) { fail(InputResult.Invalid) }

step(value: Int, state: State) (next: State) {
  next = State {
    total = state.total + decimal.fromInt(value) * state.factor
    factor = state.factor
  }
}

run(ticks: Text, initial: Text, factor: Text) (sample: Sample) {
  bytes = dever.bytes.fromText(ticks)
  state = State { total = parsed(decimal.parse(initial))
factor = parsed(decimal.parse(factor)) }
  begin = dever.time.monotonicNanos()
  final = reduce(step, bytes, state)
  end = dever.time.monotonicNanos()
  sample = Sample { elapsed_ns = end - begin
checksum = decimal.toText(final.total) }
}

continuous(ticks: Text, initial: Text, factor: Text) (samples: List<Sample>) {
  samples = [run(ticks, initial, factor), run(ticks, initial, factor), run(ticks, initial, factor), run(ticks, initial, factor), run(ticks, initial, factor), run(ticks, initial, factor), run(ticks, initial, factor), run(ticks, initial, factor), run(ticks, initial, factor), run(ticks, initial, factor)]
}