packet_port.ex

cmd = ~S"""
  ruby -e '
    STDOUT.sync = true

    def receive_input
      encoded_length = STDIN.read(4)
      return nil unless encoded_length

      length = encoded_length.unpack("N").first
      STDIN.read(length)
    end

    def send_response(value)
      response = value.inspect
      STDOUT.write([response.bytesize].pack("N"))
      STDOUT.write(response)
      true
    end

    context = binding
    while (cmd = receive_input) do
      eval(cmd, context)
    end
  '
"""

port = Port.open({:spawn, cmd}, [:binary, {:packet, 4}])

Port.command(port, "a = 1")
Port.command(port, ~S"""
  while a < 10 do
    a *= 3
  end
""")

Port.command(port, ~S"""
  send_response("response")
  send_response(a)
""")

receive do
  {^port, {:data, result}} ->
    IO.puts("Elixir got: #{inspect result}")
end

receive do
  {^port, {:data, result}} ->
    IO.puts("Elixir got: #{inspect result}")
end

Port.close(port)