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Shoulders of giants
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Fault Tolerance
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Fault Tolerance
Parallelism
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Actors/Processes
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Observer
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Supervisors
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Fault Tolerance
Hot Code Swapping
Parallelism
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Fault Tolerance
Hot Code Swapping
Distribution
Parallelism
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Fault Tolerance
Performance
Hot Code Swapping
Distribution
Parallelism
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Fault Tolerance
Performance
Hot Code Swapping
Distribution
Functional Programming
Parallelism
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Fault Tolerance
Performance
Hot Code Swapping
Distribution
Functional Programming
Parallelism
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If somebody came to me and wanted to pay me a lot of
money to build a large scale message handling system that
really had to be up all the time, could never afford to go
down for years at a time, I would unhesitatingly choose
Erlang to build it in.
Tim Bray
(Director of Web Technologies Sun Microsystems - 2008)
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2 Million Websocket Connections
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2 Million Websocket Connections
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Great Company
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Elixir and Phoenix
fast, concurrent and explicit
Tobias Pfeiffer
@PragTob
pragtob.info
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Elixir and Phoenix
fast, concurrent and explicit
Tobias Pfeiffer
@PragTob
pragtob.info
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No content
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defmodule MapDemo do
@doc """
iex> MapDemo.map [1, 2, 3, 4], fn i -> i + 1 end
[2, 3, 4, 5]
"""
def map(list, function) do
Enum.reverse(do_map([], list, function))
end
defp do_map(acc, [], _function) do
acc
end
defp do_map(acc, [head | tail], function) do
do_map([function.(head) | acc], tail, function)
end
end
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defmodule MapDemo do
@doc """
iex> MapDemo.map [1, 2, 3, 4], fn i -> i + 1 end
[2, 3, 4, 5]
"""
def map(list, function) do
Enum.reverse(do_map([], list, function))
end
defp do_map(acc, [], _function) do
acc
end
defp do_map(acc, [head | tail], function) do
do_map([function.(head) | acc], tail, function)
end
end
Ruby-like Syntax
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defmodule MapDemo do
@doc """
iex> MapDemo.map [1, 2, 3, 4], fn i -> i + 1 end
[2, 3, 4, 5]
"""
def map(list, function) do
Enum.reverse(do_map([], list, function))
end
defp do_map(acc, [], _function) do
acc
end
defp do_map(acc, [head | tail], function) do
do_map([function.(head) | acc], tail, function)
end
end
First Class Functions
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defmodule MapDemo do
@doc """
iex> MapDemo.map [1, 2, 3, 4], fn i -> i + 1 end
[2, 3, 4, 5]
"""
def map(list, function) do
Enum.reverse(do_map([], list, function))
end
defp do_map(acc, [], _function) do
acc
end
defp do_map(acc, [head | tail], function) do
do_map([function.(head) | acc], tail, function)
end
end
Pattern Matching
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defmodule Patterns do
def greet(%{name: name, age: age}) do
IO.puts("Hi there -{name}, what's up at -{age}?")
end
def greet(%{name: "Emily"}) do
IO.puts("Thanks for running Øredev for so long!")
end
def greet(%{name: name}) do
IO.puts("Hi there -{name}")
end
def greet(_) do
IO.puts("Hi")
end
end
Pattern Matching
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defmodule Patterns do
def greet(%{name: name, age: age}) do
IO.puts("Hi there -{name}, what's up at -{age}?")
end
def greet(%{name: "Emily"}) do
IO.puts("Thanks for running Øredev for so long!")
end
def greet(%{name: name}) do
IO.puts("Hi there -{name}")
end
def greet(_) do
IO.puts("Hi")
end
end
%{name: "Tobi", age: 30, something: :else}
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defmodule Patterns do
def greet(%{name: name, age: age}) do
IO.puts("Hi there -{name}, what's up at -{age}?")
end
def greet(%{name: "Emily"}) do
IO.puts("Thanks for running Øredev for so long!")
end
def greet(%{name: name}) do
IO.puts("Hi there -{name}")
end
def greet(_) do
IO.puts("Hi")
end
end
%{name: "Emily"}
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defmodule Patterns do
def greet(%{name: name, age: age}) do
IO.puts("Hi there -{name}, what's up at -{age}?")
end
def greet(%{name: "Emily"}) do
IO.puts("Thanks for running Øredev for so long!")
end
def greet(%{name: name}) do
IO.puts("Hi there -{name}")
end
def greet(_) do
IO.puts("Hi")
end
end
%{name: "Tadeáš"}
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defmodule Patterns do
def greet(%{name: name, age: age}) do
IO.puts("Hi there -{name}, what's up at -{age}?")
end
def greet(%{name: "Emily"}) do
IO.puts("Thanks for running Øredev for so long!")
end
def greet(%{name: name}) do
IO.puts("Hi there -{name}")
end
def greet(_) do
IO.puts("Hi")
end
end
["Mop"]
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defmodule MapDemo do
@doc """
iex> MapDemo.map [1, 2, 3, 4], fn i -> i + 1 end
[2, 3, 4, 5]
"""
def map(list, function) do
Enum.reverse(do_map([], list, function))
end
defp do_map(acc, [], _function) do
acc
end
defp do_map(acc, [head | tail], function) do
do_map([function.(head) | acc], tail, function)
end
end
Docs
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defmodule MapDemo do
@doc """
iex> MapDemo.map [1, 2, 3, 4], fn i -> i + 1 end
[2, 3, 4, 5]
"""
def map(list, function) do
Enum.reverse(do_map([], list, function))
end
defp do_map(acc, [], _function) do
acc
end
defp do_map(acc, [head | tail], function) do
do_map([function.(head) | acc], tail, function)
end
end
Doctests
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defmacro plug(plug, opts \\ []) do
quote do
@plugs {unquote(plug), unquote(opts), true}
end
end
Meta Programming
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defprotocol Blank do
def blank?(data)
end
defimpl Blank, for: List do
def blank?([]), do: true
def blank?(_), do: false
end
defimpl Blank, for: Map do
def blank?(map), do: map_size(map) -= 0
end
Polymorphism
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defprotocol Blank do
def blank?(data)
end
defimpl Blank, for: List do
def blank?([]), do: true
def blank?(_), do: false
end
defimpl Blank, for: Map do
def blank?(map), do: map_size(map) -= 0
end
Polymorphism
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defprotocol Blank do
def blank?(data)
end
defimpl Blank, for: List do
def blank?([]), do: true
def blank?(_), do: false
end
defimpl Blank, for: Map do
def blank?(map), do: map_size(map) -= 0
end
Polymorphism
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@spec all?(t) -: boolean
@spec all?(t, (element -> as_boolean(term))) -: boolean
def all?(enumerable, fun \\ fn x -> x end)
def all?(enumerable, fun) when is_list(enumerable) and is_function(fun, 1) do
do_all?(enumerable, fun)
end
Implemented in itself!
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@spec all?(t) -: boolean
@spec all?(t, (element -> as_boolean(term))) -: boolean
def all?(enumerable, fun \\ fn x -> x end)
def all?(enumerable, fun) when is_list(enumerable) and is_function(fun, 1) do
do_all?(enumerable, fun)
end
Optional Typespecs
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defmodule Plug do
@type opts -: tuple | atom | integer | float | [opts]
@callback init(opts) -: opts
@callback call(Plug.Conn.t(), opts) -: Plug.Conn.t()
end
“Interfaces”
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defmodule Plug do
@type opts -: tuple | atom | integer | float | [opts]
@callback init(opts) -: opts
@callback call(Plug.Conn.t(), opts) -: Plug.Conn.t()
end
“Interfaces”
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defmodule Plug.Head do
@behaviour Plug
alias Plug.Conn
def init([]), do: []
def call(%Conn{method: "HEAD"} = conn, []) do
%{conn | method: "GET"}
end
def call(conn, []), do: conn
end
“Interfaces”
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defmodule Plug.Head do
@behaviour Plug
alias Plug.Conn
def init([]), do: []
def call(%Conn{method: "HEAD"} = conn, []) do
%{conn | method: "GET"}
end
def call(conn, []), do: conn
end
“Interfaces”
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defmodule Plug.Head do
@behaviour Plug
alias Plug.Conn
def init([]), do: []
def call(%Conn{method: "HEAD"} = conn, []) do
%{conn | method: "GET"}
end
def call(conn, []), do: conn
end
“Interfaces”
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Functional Programming?
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Not Me
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Me
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2.6.5 :001 > [1, 2, 3, 4].map { |i| i + 1 }
-> [2, 3, 4, 5]
iex(2)> Enum.map [1, 2, 3, 4], fn i -> i + 1 end
[2, 3, 4, 5]
vs
Where to call functions
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Separate State & Behaviour
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Transformation
of Data
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Pipe
people = DB.find_customers
orders = Orders.for_customers(people)
tax = sales_tax(orders, 2019)
filing = prepare_filing(tax)
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filing = DB.find_customers
-> Orders.for_customers
-> sales_tax(2019)
-> prepare_filing
Pipe
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filing =
prepare_filing(sales_tax(
Orders.for_cusstomers(DB.find_customers), 2019))
Pipe
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filing =
prepare_filing(sales_tax(
Orders.for_cusstomers(DB.find_customers), 2019))
Pipe
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filing = DB.find_customers
-> Orders.for_customers
-> sales_tax(2019)
-> prepare_filing
Pipe
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person = Person.new(attributes)
do_something(person)
insert_in_db(person)
Immutable Data
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person = Person.new(attributes)
person = do_something(person)
insert_in_db(person)
Immutable Data
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Principles vs Power
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Same Input,
Same Output
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Readability
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Refactoring++
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Testing++
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connection
-> router
-> controller
-> model
-> view
Transformation
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defmodule DemoWeb.Router do
use DemoWeb, :router
scope "/", DemoWeb do
pipe_through :browser
get "/", PageController, :index
resources "/users", UserController
resources "/posts", PostController
end
end
Router
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defmodule DemoWeb.UserController do
use DemoWeb, :controller
def show(conn, %{"id" -> id}) do
user = Accounts.get_user!(id)
render(conn, "show.html", user: user)
end
end
Controller
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defmodule DemoWeb.UserController do
use DemoWeb, :controller
def show(conn, %{"id" -> id}) do
user = Accounts.get_user!(id)
render(conn, "show.html", user: user)
end
end
Context
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defmodule Demo.Accounts do
def get_user!(id) do
Repo.get!(User, id)
end
end
Context
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defmodule Demo.Accounts.User do
use Ecto.Schema
schema "users" do
field :age, :integer
field :name, :string
has_many(:posts, Blogging.Post)
timestamps()
end
end
Schema
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defmodule DemoWeb.UserController do
use DemoWeb, :controller
def show(conn, %{"id" -> id}) do
user = Accounts.get_user!(id)
render(conn, "show.html", user: user)
end
end
Controller
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defmodule DemoWeb.UserView do
use DemoWeb, :view
def display(user) do
"-{user.name} (-{user.age})"
end
end
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Show User-/h1>
-
Name:-/strong>
<%= @user.name %>
-/li>
-
Age:-/strong>
<%= @user.age %>
-/li>
-/ul>
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No content
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def new_changeset(model, params \\ %{}) do
model
-> cast(params, ~w(name username), [])
-> unique_constraint(:username)
-> validate_length(:username, min: 1, max: 20)
end
def registration_changeset(model, params) do
model
-> new_changeset(params)
-> cast(params, ~w(password), [])
-> validate_length(:password, min: 6, max: 100)
-> put_pass_hash()
end
Changesets
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def new_changeset(model, params \\ %{}) do
model
-> cast(params, ~w(name username), [])
-> unique_constraint(:username)
-> validate_length(:username, min: 1, max: 20)
end
def registration_changeset(model, params) do
model
-> new_changeset(params)
-> cast(params, ~w(password), [])
-> validate_length(:password, min: 6, max: 100)
-> put_pass_hash()
end
Changesets
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def new_changeset(model, params \\ %{}) do
model
-> cast(params, ~w(name username), [])
-> unique_constraint(:username)
-> validate_length(:username, min: 1, max: 20)
end
def registration_changeset(model, params) do
model
-> new_changeset(params)
-> cast(params, ~w(password), [])
-> validate_length(:password, min: 6, max: 100)
-> put_pass_hash()
end
Changesets
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def new_changeset(model, params \\ %{}) do
model
-> cast(params, ~w(name username), [])
-> unique_constraint(:username)
-> validate_length(:username, min: 1, max: 20)
end
def registration_changeset(model, params) do
model
-> new_changeset(params)
-> cast(params, ~w(password), [])
-> validate_length(:password, min: 6, max: 100)
-> put_pass_hash()
end
Changesets
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The right tool
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Liveview!
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def handle_info(:tick, socket) do
game = Game.update(socket.assigns.game)
case game.state do
:ok ->
socket = schedule_tick(socket)
{:noreply, assign(socket, game: game)}
:end ->
{:noreply, assign(socket, game: game)}
end
end
def handle_event("keydown", _key, socket) do
game = socket.assigns.game
case game.state do
:ok -> {:noreply, assign(socket, game: Game.flap(game))}
_ -> {:noreply, new_game(socket)}
end
end
Liveview!
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-/div>
<%= for pipe -- @game.pipes do %>
-/div>
<% end %>
Liveview!
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-/div>
<%= for pipe -- @game.pipes do %>
-/div>
<% end %>
Liveview!
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Demo!
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So we all go and do Elixir
and Phoenix now?
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Baggage
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An exciting land
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Thank you!
Tobias Pfeiffer
@PragTob
pragtob.info
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Photo Attribution
●
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– https://www.flickr.com/photos/mmmswan/8918529543/
●
CC BY 2.0
– https://flic.kr/p/eKGRRJ
●
CC BY-NC 2.0
– https://www.flickr.com/photos/-jule/2728475835/
– https://flic.kr/p/emoKPd
●
CC BY-NC-ND 2.0
– https://flic.kr/p/eyC7ZT
– https://www.flickr.com/photos/75487768@N04/14029339573/
– https://flic.kr/p/bG2r2D
●
CC BY-SA 2.0
– https://commons.wikimedia.org/wiki/File:Heckert_GNU_white.svg
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