Tutorial for Elixir. Why it is awesome and why you should dive into the ecosystem.

1. Bootstrap
EASY FUN FOR BUSY DEVELOPERS
|> Elixir

2. YET
ANOTHER
PROGRAMMING
LANGUANGE?
Y
A
P
L

3. DON’T RUN AWAY
Elixir is special!

4. Elixir in a Nutshell
= +
Elixir in a Nutshell
+

5. PROGRAMMERS OFTEN FEEL JOY WHEN THEY CAN CONCENTRATE ON THE
CREATIVE SIDE OF PROGRAMMING, SO RUBY IS DESIGNED TO
MAKE PROGRAMMERS HAPPY. I CONSIDER A PROGRAMMING
LANGUAGE AS A USER INTERFACE, SO IT SHOULD FOLLOW THE
PRINCIPLES OF USER INTERFACE.
Yukihiro Matsumoto, Ruby Inventor
Why Ruby is awesome

6. Principle of Conciseness
Principle of Consistency
Principle of Flexibility
Why Ruby is awesome

7. THE AXD301 HAS ACHIEVED A NINE NINES RELIABILITY (YES, YOU
READ THAT RIGHT, 99.9999999%). LET’S PUT THIS IN
CONTEXT: 5 NINES IS RECKONED TO BE GOOD (5.2 MINUTES OF
DOWNTIME/YEAR). 7 NINES ALMOST UNACHIEVABLE ... BUT WE
DID 9.
Joe Armstrong, Erlang Designer
Why Erlang is awesome

8. Battle-proven BEAM and OTP
Ever seen WhatsApp crash?
Reactive before Reactive-is-HipTm
Actors before Actors-are—HipTm
Why Erlang is awesome

9. Why Clojure is awesome
Because Rich Hickey is always right

10. SO…WHY NOT DO RUBY, ERLANG OR CLOJURE?

11. WHY NOT USE RUBY?
SPEED, CONCURRENCY, SCALABILITY

12. WHY NOT USE ERLANG?
SYNTAX, BAROQUE TOOLING

13. WHY NOT USE CLOJURE?
…NO REASON, REALLY. GO AHEAD USE IT!

14. Scalability, lightweight Threads
Fault-tolerance, Supervisor
Functional, immutable
DSLs using Meta-Programming
Mix, Hex, ExUnit,…
REPL for easy learning
Why Elixir is awesome

15. Scalability, lightweight Threads
Fault-tolerance, Supervisor
Functional, immutable
DSLs using Meta-Programming
Mix, Hex, ExUnit,…
REPL for easy learning
Why Elixir is awesome

16. 100000 Processes
1..100_000
|> Enum.map(&(Task.async(
fn -> &1 * &1 end
)))
|> Enum.map(&Task.await/1)

17. [1, 4, 9, 16, 25, 36, 49, 64, 81, 100,
121, 144, 169, 196, 225, 256, 289, 324,
361, 400, 441, 484, 529, 576, 625, 676,
729, 784, 841, 900, 961, 1024, 1089,
1156, 1225, 1296, 1369, 1444, 1521,
1600, 1681, 1764, 1849, 1936, 2025, 2116,
2209, 2304, 2401, 2500, ...]
100000 Processes

18. 1..100_000
|> Enum.map(&(Task.async(
fn -> &1 * &1 end
)))
|> Enum.map(&Task.await/1)
?what?
100000 Processes

19. Quick
syntax
bootcamp

20. Creating a project
$ mix new demo
$ cd demo
$ mix test

21. Read Eval Print Loop
$ iex -S mix
Erlang/OTP 18 …
Interactive Elixir (1.2.4) - press Ctrl+C to
exit (type h() ENTER for help)
iex(1)> IO.puts “Hello Elixir”
Hello Elixir
:ok

22. Transform - don’t mutate
10
|> fib
|> IO.puts
IO.puts(fib(10))
transformation pipeline

23. Declaring functions
def fib(0), do: 0
def fib(0) do
0
end
(n-1) + fib(n-2)
end
same thing

24. Pattern matching
def fib(0), do: 0
def fib(1), do: 1
def fib(n) when n > 1
iex> fib(1)
pattern matching

25. Guard expressions
def fib(n) when n > 1 do
fib(n-1) + fib(n-2)
end
guard expression

26. iex> fib(-3)
** (FunctionClauseError)
no function clause
matching in fib/1
(fibnew) lib/fib2.ex:2: fib(-3)
Things go wrong

27. Anonymous functions
fn n ->
n + 2
end
&( &1 + 2 )
same thing

28. Function shortcuts
IO.puts/2
def puts(device, item)
/2 denotes the number of args

29. Compile-time structural decomposition
def sqrt([h | t]), do: …
iex> sqrt([1, 2, 3, 4 ])

30. Show me the code
Demo

31. ELIXIR APPLICATION DESIGN
APPLICATIONS, SUPERVISORS, PROCESSES

32. Shared resources Shared state Shared stability
PROCESS
SHARED STATE

33. Shared nothing Message passing
PROCESS
PROCESS
PROCESS
PROCESS
PROCESS
PROCESS
PROCESS
PROCESS
PROCESS
PROCESS
PROCESS
PROCESS
PROCESS

34. Abstractions for Resilience
Agent…abstractions around state
GenServer…long-running, messaging
Supervisor…let it crash
Application…just think component

35. Abstractions for Resilience
Agent…abstractions around state
GenServer…long-running, messaging
Supervisor…let it crash
Application…just think component

36. Message-based design using GenServer
BA
GenServer.start_link
{:ok, #PID<0.112.0>}

37. Message-based design using GenServer
BA
GenServer.call(B, {:sum, 1..3})

38. Message-based design using GenServer
BA
handle_call({:sum, 1..3}, from, state)

39. Message-based design using GenServer
BA
{:reply, {:ok, 6}, new_state)

40. GenServer
Demo

42. Move risk to the bottom of the supervision tree
APPLICATION
SUPERVISOR WORKER C
WORKER A WORKER B Here be dragons…
FILE IO DB ACCESS

43. Supervisors watch their children
APPLICATION
SUPERVISOR WORKER C
WORKER A WORKER B
:one_for_one!

44. :one_for_one replaces failed process
APPLICATION
SUPERVISOR WORKER C
WORKER A WORKER B WORKER B’ Auto-restart

45. Supervisor
Demo

46. Processes are distributed across nodes
PROCESS
PROCESS
PROCESS
PROCESS
PROCESS
PROCESS
PROCESS
PROCESS
PROCESS
PROCESS
PROCESS
PROCESS
PROCESS
:”one@foo”
:”two@foo”

47. Nodes and distribution
Demo

48. MORE COOL FEATURES
TEASERS ONLY

49. Testing documentation
@doc """
iex> sieve(10)
[2, 3, 5, 7]
"""
def sieve(n) do
...
end
defmodule Test do
use ExUnit.Case
doctest
…
end

50. Hygienic Macros
defmacro time([do: body]) do
quote do
s = :os.system_time(…)
unquote(body)
f = :os.system_time(…)
info(“Took #{s-f} ms")
end
end
time do
IO.puts "Something"
:timer.sleep(100)
end
[info] Took 101 ms

51. There is so much more

52. Protocols
Sigils
Umbrella projects
Ecto
Phoenix
Hot code replacement

53. SHOULD WE ALL START
BUILDING EVERYTHING
WITH ELIXIR?

55. WELL….MAYBE NOT?!

56. New insights and ideas
Clean patterns
Architecture for IoT
Vibrant Community

57. 学⼀一⻔门语⾔言，就是多⼀一个观察世界的窗户。
To learn a language is to have one more window from which to look at the world

58. Elixir Homepage, http://elixir-lang.org/
Dave Thomas, Programming Elixir
Fred Hebert, Stuff Goes Bad: Erlang in Anger
José Valim, Introduction to Elixir https://
youtu.be/41PvAPSX0wg
Slides + Code, https://git.io/vKUGc
Do you want to know more?

59. Thank you very much!
<david.schmitz@senacor.com> @koenighotze