Concurrent elixir downloader with some fault toleration

download.ex

defmodule Dl do
  require Logger

  def download(url) do
    case HTTPoison.get(url) do
      {:ok, response} ->
        case response.status_code do
          200 ->
            {:ok, response.body}

          _ ->
            {:error, {response.status_code, response.request_url, response.body}}
        end
    end
  end

  def bd do
    Logger.info("Starting")
    ["https://slashdot.org", "https://news.ycombinator.com", "http://google.com"]
    |> Flow.from_enumerable()
    |> Flow.map(&download/1)
    |> Flow.partition()
    |> Flow.map(fn result ->
      case result do
        {:ok, body} ->
          {:ok, file} = File.open("out_path", [:write])
          :ok = IO.binwrite(file, body)
          :ok = File.close(file)

        {:error, error} ->
          Logger.error("Error:  #{inspect error}")

        _ ->
          Logger.info("Error Unhandled")
      end
    end)
    |> Flow.run()
  end
end