Elixir - Part 1

A talk about Elixir and OTP given at Codeaholics in Hong Kong on August 12th 2015

Transcript

1. Real-time Apps With Elixir Matthew Rudy Jacobs @ Codeaholics HK
2. THE PROBLEM SPACE
3. Line 100s of millions of online users Can’t lose a message Don’t want downtime
4. Uber 100,000s online users Can’t lose a message Don’t want downtime
5. GoGoVan ? online users Can’t lose a message Don’t want downtime
6. THE SOLUTION?
7. Erlang The Movie
8. Ericsson (in 1998) 99.9999999% UPTIME 32MS / YEAR
9. Ericsson (in 1998) 99.9999999% UPTIME < 1SECOND / 20 YEARS
11. Whatsapp 64 billion messages per day 700 million monthly active users 1000 servers doing the work
12. 4 Parts
13. Erlang Elixir OTP Phoenix
14. Part 1 Erlang
15. WHAT IS ERLANG?
16. Erlang • functional • concurrent • realtime
17. Erlang • pattern matching • message passing • actors • hot code reloading
18. -module(roman). -export([to_roman/1]). to_roman(0) -> []; to_roman(X) when X >= 1000 -> [$M | to_roman(X - 1000)]; to_roman(X) when X >= 100 -> digit(X div 100, $C, $D, $M) ++ to_roman(X rem 100); to_roman(X) when X >= 10 -> digit(X div 10, $X, $L, $C) ++ to_roman(X rem 10); to_roman(X) when X >= 1 -> digit(X, $I, $V, $X). digit(1, X, _, _) -> [X]; digit(2, X, _, _) -> [X, X]; digit(3, X, _, _) -> [X, X, X]; digit(4, X, Y, _) -> [X, Y]; digit(5, _, Y, _) -> [Y]; digit(6, X, Y, _) -> [Y, X]; digit(7, X, Y, _) -> [Y, X, X]; digit(8, X, Y, _) -> [Y, X, X, X]; digit(9, X, _, Z) -> [X, Z]. Complex? Ugly?
20. Part 2 OTP
21. OTP IS A FRAMEWORK
22. OTP IS A SET OF CONVENTIONS
23. YOUR APPLICATION IS MADE OF “SERVERS” “AGENTS” AND “STATE MACHINES” KEPT ALIVE BY A COMPLICATED TREE OF SUPERVISORS
25. Part 3 Elixir
26. Jose Valim
27. #4 Rails Contributor
28. Creator of Devise
29. Creator of Elixir
30. “I felt the same way I felt when I first saw Ruby.”
31. ERLANG AND RUBY HAD A BABY
32. %%% erlang -module(recursve). -export([fac/1]). fac(N) when N == 0 -> 1; fac(N) when N > 0 -> N*fac(N-1). # Ruby module Recursive def fac(n) return 1 if n == 0 fail ArgumentError unless n > 0 n*fac(n-1) end end
33. # Elixir defmodule Recursive do def fac(n) when n == 0, do: 1 def fac(n) when n > 0 do n*fac(n-1) end end
34. # Elixir - with tail call defmodule Recursive do def fac(0), do: 1 def fac(n) when n > 0 do fac(n, 1) end defp fac(1, acc), do: acc defp fac(n, acc) do fac(n-1, acc*n) end end
35. “str”<>”ings”
36. :atoms
37. "with #{:interpolation}"
38. [:list, “type”]
39. {:tuple, “type”}
40. [key: “word”, list: “…”]
41. %{map: “is”, like: “a hash”}
42. defmodule My.Module do def exported() do 42 end defp private() do 76 end end
43. [head|tail] = [:a, :b, :c]
44. defmodule Math do def sum([head|tail], acc) do sum(tail, head + acc) end def sum_list([], acc) do acc end end
45. bessy = %{ type: “cow”, name: “bessy” } %{name: name} = bessy name == “bessy”
46. fn x -> 2*x end
47. list = [1,3,3,7] Enum.sum( Enum.map(list, fn x -> x*x end) ) # 68
48. [1,3,3,7] |> Enum.map(fn x -> x*x end) |> Enum.sum # 68
49. > iex
50. Part 4 Phoenix
51. Elixir on Phoenix
52. Phoenix Ecto for the database Plug for routing Channels for websockets
53. mix phoenix.new phoenix_play
54. MORE NEXT TIME
55. Appendix A Thoughts
56. Gateway Todos Users Auth SERVICES OVER HTTP Mailer Search •HTTP •Ports •Monitoring •Scaling •Logging Issues
57. Gateway Todos Users Auth A SINGLE OTP SYSTEM Mailer Search •HTTP •Ports •Monitoring •Scaling •Logging Issues
58. Ruby people finally with technology that can scale
59. PEPE Postgres Elixir Phoenix Ember
60. Appendix B Addendum
62. THANKS
64. COME WORK AT GOGOVAN!!!