Problem: Get cars from different vendors for a pickup and destination. Given each vendor has set prices for distances/places.

cars_controller.ex

# ...
  def index(conn, params) do
    model = 
     Enum.map(vendor_ids, fn(vendor_id) ->
      Task.async(fn() ->
        Cabs.find_with_fare(params, vendor_id) 
        # [ %Cab{price: 1, distance: 2},..]
        # Does some calculation based on results from different tables.
      end)
    end)
    |> Enum.map(fn(task) ->
      Task.await(task)
    end)
    |> List.flatten

    conn
    |> render("index.json", model: model)
  end
  
  def vendor_ids do
   #...
  end
# ...