Elixir Genserver#1

stack_genserver.ex

defmodule StackGenserver do
  use GenServer

  # Client

  def start_link(default) when is_list(default) do
    GenServer.start_link(__MODULE__, default)
  end

  def push(pid, item) do
    GenServer.call(pid, {:push, item})
  end

  def pop(pid) do
    GenServer.call(pid, :pop)
  end

  # Server (callbacks)

  @impl true
  def init(stack) do
    {:ok, stack}
  end

  @impl true
  def handle_call(:pop, _from, state) do
    {value, list} = List.pop_at(state, 0)

    {:reply, value, list}
  end

  @impl true
  def handle_call({:push, item}, _from, state) do
    {:reply, [item | state], [item | state]}
  end
end