ll_cat_store.ex

defmodule LlCatStore do

  def loop(cats) do
    receive do
      {:add, cat} ->
          IO.puts "adding cat #{cat}"
          loop([cat | cats])
      {:remove, cat} ->
          IO.puts "removing cat #{cat}"
          loop(remove_cat(cat, cats))
      {:list} ->
          Enum.each(cats, fn(c) -> IO.puts("Cat: #{c}") end)
          loop(cats)
    end
  end

  def remove_cat(cat, current_cats) do
     case cat in current_cats do
        true ->
          List.delete(current_cats, cat)
        false ->
          current_cats
     end
  end

  def start() do
    spawn(fn -> loop(["BigglesWorth"]) end)
  end
end

#iex(1)> foo = LlCatStore.start
##PID<0.94.0>
#iex(2)> send(foo, {:add, "Fuzzy"})
#adding cat Fuzzy
#{:add, "Fuzzy"}
#iex(3)> send(foo, {:add, "LuLu"})
#adding cat LuLu
#{:add, "LuLu"}
#iex(4)> send(foo, {:add, "JohnnyQuest"})
#adding cat JohnnyQuest
#{:add, "JohnnyQuest"}
#iex(5)> send(foo, {:remove, "JohnnyQuest"})
#removing cat JohnnyQuest
#{:remove, "JohnnyQuest"}
#iex(6)> send(foo, {:list})
#Cat: LuLu
#Cat: Fuzzy
#Cat: BigglesWorth
#{:list}