This snippet is for learning Process in Elixir, with this snippet you can calculator basic arithmetic operation.

Calculator By Elixir Process.ex

defmodule Cal do
  def start do
    spawn(fn -> loop(0) end)
  end

  def view(server_pid) do
    send(server_pid, {:view, self()})

    receive do
      {:response, value} ->
        value
    end
  end

  def add(server_pid, value) do
    send(server_pid, {:add, value})
    view(server_pid)
  end
  def sub(server_pid, value) do
    send(server_pid, {:sub, value})
    view(server_pid)
  end
  def mult(server_pid, value) do
    send(server_pid, {:mult, value})
    view(server_pid)
  end
  def div(server_pid, value) do
    send(server_pid, {:div, value})
    view(server_pid)
  end

  defp loop(current_value) do
    new_value =
      receive do
        {:view, caller_pid} ->
          send(caller_pid, {:response, current_value})
          current_value

        {:add, value} ->
          current_value + value

        {:sub, value} ->
          current_value - value

        {:mult, value} ->
          current_value * value

        {:div, value} ->
          current_value / value

        _ ->
          IO.puts("Invalid Message")
      end

    loop(new_value)
  end
end

# p = Cal.start
# Cal.add(p, 5)  // 5
# Cal.mult(p, 5) // 25