Chapter 1

Sum server using Agent

defmodule SumAgent do
  use Agent

  def start_link do
    Agent.start_link(fn -> nil end, name: __MODULE__)
  end

  def sum(a, b) do
    Agent.get(__MODULE__, fn _ -> a + b end)
  end
end

{:module, SumAgent, <<70, 79, 82, 49, 0, 0, 10, ...>>, {:sum, 2}}

SumAgent.start_link()

{:ok, #PID<0.166.0>}

SumAgent.sum(5, 3)

8