Code examples for ruby meetup - Elixir edition

agent_example.exs

{:ok, agent} = Agent.start_link(fn -> [] end)

Agent.get(agent, fn list -> list end) # => []

Agent.update(agent, fn list -> ["eggs"|list] end) # => :ok

Agent.get(agent, fn list -> list end) # => ["eggs"]

Agent.stop(agent) # => :ok

elixir_processes.md

In one directory

iex --sname one

In another directory

iex --sname two

In IEx one

Node.connect :"two@COMPUTER_NAME"
Node.list

In IEx two

Node.list

List the files of the working directory of the other Node

fun = fn -> IO.puts(Enum.join(File.ls!, ",")) end
Node.spawn(:"one@COMPUTER_NAME", fun)
Node.spawn(:"two@COMPUTER_NAME", fun)

For Nodes in different machines start IEx with full name and a common secret cookie

iex --name one@DOMAIN_OR_IP --cookie SECRET_COOKIE
iex --name two@DOMAIN_OR_IP --cookie SECRET_COOKIE

gen_server_stack_example.exs

defmodule GenServerStack do
  use GenServer

  def handle_call(:pop, _from, [h|t]) do
    {:reply, h, t}
  end

  def handle_cast({:push, item}, state) do
    {:noreply, [item|state]}
  end
end

{:ok, pid} = GenServer.start_link(GenServerStack, [:hello])

GenServer.call(pid, :pop) # => :hello

GenServer.cast(pid, {:push, :world}) # => :ok

GenServer.call(pid, :pop) # => :world

leak_state.rb

class Leak
  attr_reader :state
  
  def initialize
    @state = {}
  end
end

leak = Leak.new
leak.state[:inject] = :state
leak.state # => { :inject => :state }

stack_example.exs

defmodule Stack do
  def init(state) do
    new_state = state
    receive do
      { client, :pop } ->
        [h | new_state] = state
        send client, { self(), :result, h }
      { client, :push, value } ->
        new_state = [value | state]
        send client, { self(), :ok }
    end
    init(new_state)
  end
end

pid = spawn(Stack, :init, [[:hello]])

send(pid, {self(), :pop})

send(pid, {self(), :push, :world})

send(pid, {self(), :pop})

flush

task_example.exs

fun = fn -> 
        IO.puts "Started long function"
        :timer.sleep(2000)
        IO.puts "Finished long function"  
      end

fun.()

Task.async(fun)