The Mix Tool

• Easier to navigate project files.
• Facilitates collaboration from other developers on the team.

Using Mix to Create a New project

• build tool.

mix new budget

The mix run command.

mix run -e "Budget.current_balance(100, 20) |> IO.puts"

What does the mix run command does.

1. Compiles the budget application.
2. Loads the generated bytecode into the Erlang Virtual Machine.
3. Detects the -e option and evaluates the argument as code.

The Third Party Dependencies with Mix Projects

mix run -e "Budget.Conversion.from_euro_to_dollar(15) | IO.puts"

Declaring Third-party Dependencies

defmodule Budget.Mixfile do
    defp deps do
        [{:httpoison, "~> 0.10.0"}, {:poison, "~> 3.0"}]
    end
end

mix deps.get

Making HTTP Calls with the HTTPoison Library

defmodule Budget.Conversion do
    def from_euro_to_dollar(amount) do
        url = cs-currency-rates.herokuapp.com/currency-rates"
        case HTTPoison.get(url) do
            {:ok, response} -> parse(response) |> convert(amount)
            {:error, _} -> "Error fetching rates"
        end
    end

    defp parse(%{status_code: 200, body: json_response}) do
        Poison.Parser.parse(json_response)
    end

    defp convert({:ok, rates}, amount) do
        rate = find_euro(rates)
        amount * rate
    end

    defp find_euro([%{"currency" => "euro", "rate" => rate} | _] do
        rate
    end

    defp find_euro([_ | tail]) do
        find_euro(tail)
    end

    defp find_euro([]) do
        raise "No rate found for Euro"
    end

end

Running the complete program

mix run -e "Budget.Conversion.from_euro_to_dollar(15) |> IO.puts"