TylerPachal

def join_game(user_id, game_id) do
  with {:ok, user} <- Users.get(user_id), 
       {:ok, game} <- Games.get(game_id),
       false       <- Game.is_full?(game),
       false       <- Game.is_started?(game),
       true        <- User.has_permission?(user, game)
do
  Game.add_user(game, user)
else
  :not_found -> {:error, "User or game not found"}

TylerPachal

with {:width, {:ok, width}}   <- {:width, Map.fetch(opts, :width)},
     {:height, {:ok, height}} <- {:height, Map.fetch(opts, :height)}
do
  {:ok, width * height}
else
  {:width, :error} -> {:error, :missing_width}
  {:height, :error} -> {:error, :missing_height}
end

TylerPachal

with {:ok, width}  <- Map.fetch(opts, :width),
     {:ok, height} <- Map.fetch(opts, :height)
do
  {:ok, width * height}
else
  :error -> {:error, :wrong_data}
end

TylerPachal

defmodule Api do
  require Record

  # Wrap the Erlang Record to make the request_uri parameter easier to access
  Record.defrecord :httpd, Record.extract(:mod, from_lib: "inets/include/httpd.hrl")

  def child_spec(_) do
    opts = [
      server_name: 'Api', 
      server_root: '/tmp',

TylerPachal

def init(:ok) do
  children =
    [
      kafka_producer_spec(),
      kafka_consumer_spec(),
      other_thing_spec(),
      Api # Start the Api from the child_spec() function defined in that module
    ]
    end

TylerPachal

def application do
  [
    extra_applications: [:logger, :inets],
    mod: {MyModule, []}
  ]
end

TylerPachal

# You don't always need pattern matching
is_admin = Map.get(user, "is_admin") || false

TylerPachal

# Using match?/2 with a guard statement
user = User.find(123)
can_access = match?(%{role: r, name: "tyler"} when r in ["owner", "admin"], user)
if can_access do
  # 200
else
  # 403
end

TylerPachal

# Pattern matching with Kernel.match?/2
my_bool = match?(%{foo: _, bar: _}, my_map)

TylerPachal

# Pattern matching with a case statement
my_bool = case my_map do
  %{foo: _, bar: _} -> true
  _ -> false
end