CatWhale's Guide to Elixir

A humorous, historical, hasty introduction to the Elixir programming language.

Transcript

1. Friday, September 6, 13
2. ELIXIR IT’S WEBSCALE BY: ZANDER HILL - 2013 Friday, September 6, 13
3. ZANDER HILL HUMANITIES TRAINED RUBYIST SOFTWARE ENGINEER AT RENTPATH.COM TWITTER: @_ZPH GITHUB: ZPH ZANDER@CIVET.WS Friday, September 6, 13
4. defmodule Say do def hello(thing) do IO.puts "Hello #{thing}" end end Say.hello("PGHRb") ================== iex(1)> Say.hello("PGHrb") Hello PGHrb :ok Friday, September 6, 13
5. Friday, September 6, 13
6. ERLANG FUNCTIONAL LANGUAGE CONCURRENCY HOT CODE LOADING PATTERN MATCHING PERFORMANT IN CRITICAL SITUATIONS Friday, September 6, 13
7. ERLANG HTTP://WWW.SLIDESHARE.NET/ARBOW/COMPARING-CPP-AND-ERLANG-FOR-MOTOROLA-TELECOMS-SOFTWARE Friday, September 6, 13
8. HTTP://WWW.SLIDESHARE.NET/ARBOW/COMPARING-CPP-AND-ERLANG-FOR-MOTOROLA-TELECOMS-SOFTWARE Never completely fails, still handles 25,000 queries/sec Friday, September 6, 13
9. ERLANG, YAY!!! FORGET RUBY FORGET ELIXIR LET’S LEARN ERLANG!!! Friday, September 6, 13
10. WAT!!! Friday, September 6, 13
11. CAT-WHALE SEZ GET TO THE POINT!!! MOAR CODE LESS LOLZ Friday, September 6, 13
12. SO... ABOUT THIS ELIXIR Friday, September 6, 13
13. JOSE VALIM DAVE THOMAS JOE ARMSTRONG Friday, September 6, 13
14. JOSE VALIM AUTHOR OF ELIXIR 2010 RUBY HERO RAILS CORE, SIMPLE_FORM, DEVISE ALL AROUND SHARP RUBYIST Friday, September 6, 13
15. DAVE THOMAS I’m a language nut. I love trying them out, and I love thinking about their design and implementation. (I know, it’s sad.) I came across Ruby in 1998 because I was an avid reader of comp.lang.misc (ask your parents). I downloaded it, compiled it, and fell in love. As with any time you fall in love, it’s difficult to explain why. It just worked the way I work, and it had enough depth to keep me interested. ... - Foreword to Programming Elixir Friday, September 6, 13
16. Fast forward 15 years. All that time I’d been looking for something new that gave me the same feeling. I came across Elixir a while back, but for some reason never got sucked in. But a few months ago I was chatting with Corey Haines. I was bemoaning the fact that I wanted to find a way to show people functional programming concepts without the kind of academic trappings those books seem to attract. He told me to look again at Elixir. I did, and I felt the same way I felt when I first saw Ruby. ... - Foreword to Programming Elixir DAVE THOMAS Friday, September 6, 13
17. DAVE THOMAS So now I’m dangerous. I want other people to see just how great this is. I want to evangelize. So my first step is to write a book. - Foreword to Programming Elixir Friday, September 6, 13
18. JOE ARMSTRONG AND NO GOOD BOOK GOES UNPUNISHED... SO HERE’S THE MOVIE!!! Friday, September 6, 13
19. DEVELOPED ERLANG FOR ERICSSON RELEASED FIRST VERSION OF ERLANG IN 1986. ERICSSON OPEN-SOURCED ERLANG IN 1998. JOE ARMSTRONG Friday, September 6, 13
20. “With both Pragmatic Press and O'Reilly racing to get into Elixir I knew something was happening on the Erlang VM, and I didn’t know about this. Boy am I out of touch.” - Blog Post - http://joearms.github.io/2013/05/31/a-week-with-elixir.html JOE ARMSTRONG Friday, September 6, 13
21. JOE ARMSTRONG “I downloaded elixir last week and started playing … It didn’t take long, but pretty soon my gut feeling kicked in. This is good shit.” - Blog Post - http://joearms.github.io/2013/05/31/a-week-with-elixir.html Friday, September 6, 13
22. “What Elixir brings to the table is a complete different surface syntax, inspired by Ruby. What you might call a ‘non-scary’ syntax, and a load of extra goodies.” - Blog Post - http://joearms.github.io/2013/05/31/a-week-with-elixir.html JOE ARMSTRONG Friday, September 6, 13
23. “I’ll just say that Elixir has got a heck of lot of things right, and the good things far outweigh the bad things.” “This has been my first week with Elixir, and I’m pretty excited.” - Blog Post - http://joearms.github.io/2013/05/31/a-week-with-elixir.html JOE ARMSTRONG Friday, September 6, 13
24. ELIXIR IT’S WEBSCALE* *: SERIOUSLY, IT’S TELEPHONY OLD SCHOOL RUGGED Friday, September 6, 13
25. WEBSCALE? DISTRIBUTED, RELIABLE, SOFT REAL-TIME CONCURRENT SYSTEMS. TELECOMMUNICATION SYSTEMS, E.G. CONTROLLING A SWITCH OR CONVERTING PROTOCOLS. SERVERS FOR INTERNET APPLICATIONS, E.G. A MAIL TRANSFER AGENT, AN IMAP-4 SERVER, AN HTTP SERVER OR A WAP STACK. TELECOMMUNICATION APPLICATIONS, E.G. HANDLING MOBILITY IN A MOBILE NETWORK OR PROVIDING UNIFIED MESSAGING. DATABASE APPLICATIONS WHICH REQUIRE SOFT REALTIME BEHAVIOUR. HTTP://WWW.ERLANG.ORG/FAQ/INTRODUCTION.HTML#ID49576 Friday, September 6, 13
26. WEBSCALE? HTTP://WWW.ERLANG.ORG/FAQ/INTRODUCTION.HTML#ID49576 Friday, September 6, 13
27. Friday, September 6, 13
28. ELIXIR BASICS LIKE JRUBY, NOT LIKE COFFEESCRIPT NAMESPACING VIA MODULES AND FUNCTIONS IMMUTABLE RECURSIVE 1 defmodule JsonParsing do 2 3 def get_score(username) do 4 get(username) |> extract_types |> Count.sum 5 end 6 7 # Helper Methods 8 def get(username) do 9 get_request(username) |> process_response_body 10 end 11 12 def process_url(username) do 13 "https://example.com/#{username}.json" 14 end 15 16 def get_request(username) do 17 HTTPotion.start 18 HTTPotion.get process_url(username) 19 end 20 21 def process_response_body(response) do 22 JSON.decode(response.body) 23 end 24 25 26 def extract_types(hash) do 27 {_, h2} = hash 28 Enum.map(h2, fn(x) -> Count.points HashDict.get(x, "type") end ) 29 end 30 end 31 32 defmodule Count do 33 def points(type) do 34 converter = fn 35 "EventA" -> 5 36 "EventB" -> 3 37 _ -> 1 38 end 39 converter.(type) 40 end 41 42 def sum([], total // 0), do: total 43 def sum([ head | tail ], total), do: sum(tail, head+total) 44 end Friday, September 6, 13
29. ELIXIR IS EVERYTHING GOOD ABOUT ERLANG AND NONE — ALMOST NONE — OF THE BAD. THAT’S A BOLD STATEMENT, RIGHT? ELIXIR IS WHAT WOULD HAPPEN IF ERLANG, CLOJURE, AND RUBY SOMEHOW HAD A BABY AND IT WASN’T AN ACCIDENT. -- DEVIN TORRES HTTP://DEVINTORR.ES/BLOG/2013/01/22/THE- EXCITEMENT-OF-ELIXIR/ Friday, September 6, 13
30. PIPE OPERATOR 3 # Without Pipe Operator 4 def get_score(username) do 5 Count.sum(extract_types(get(username))) 6 end 7 8 # With Pipe Operator 9 def get_score(username) do 10 get(username) |> extract_types |> Count.sum 11 end Friday, September 6, 13
31. PATTERN MATCHING 1 converter = fn 2 "EventA" -> 5 3 "EventB" -> 3 4 _ -> 1 5 end 6 converter.(“EventA”) #=> 5 Friday, September 6, 13
32. USE ERLANG LIBRARIES defmodule GitHub do ... def process_response_body(body) do json = :jsx.decode to_binary(body) json2 = Enum.map json, fn ({k, v}) -> { binary_to_atom(k), v } end :orddict.from_list json2 end end Friday, September 6, 13
33. ELIXIR INSTALLATION # OSX brew tap homebrew/versions brew install erlang-r16 ....wait.... brew link erlang-r16 brew install elixir # Arch yaourt -S elixir # Fedora sudo yum -y install elixir http://elixir-lang.org/getting_started/1.html Friday, September 6, 13
34. ELIXIR WORKFLOW (IN VIM & TMUX) # Install vim-elixir # Add to .vimrc nnoremap <leader>e :!elixir %<CR> nnoremap <leader>ee :!iex -r % -S mix<CR> # Use this in shell for repl $ iex -r lib/concurrency.ex -S mix # Use this in shell for tests $ elixir test/concurrency_test.ex $ mix test Friday, September 6, 13
35. ELIXIR WORKFLOW (IN VIM & TMUX) Friday, September 6, 13
36. PSEUDO-LIVE CODING #Calculate the area of a rectangle #create a function and assign to variable area = fn(w, h) -> w * h end # call function area.(3, 5) #=> 15 Friday, September 6, 13
37. Code.load_file("lib/concurrency_pre.ex") ExUnit.start defmodule AreaTest do use ExUnit.Case, async: true test "area" do area = fn(w, h) -> w * h end assert area.(3,5) == 15 end end beastie:concurrency elixir test/concurrency_pre_test.exs . Finished in 0.08 seconds (0.08s on load, 0.00s on tests) 1 tests, 0 failures TESTS (VERSION 1) Friday, September 6, 13
38. # http://learnxinyminutes.com/docs/elixir/ defmodule Concurrency do def area_loop do receive do {:rectangle, w, h} -> IO.puts("Area = #{w * h}") area_loop() {:circle, r} -> IO.puts("Area = #{ :math.pi * r*r }") area_loop() end end def start do spawn(fn -> Concurrency.area_loop() end) end end Friday, September 6, 13
39. pid = Concurrency.start pid <- {:rectangle, 3, 5} pid <- {:circle, 5} beastie:concurrency iex -r "lib/concurrency.ex" iex(1)> pid = Concurrency.start #PID<0.45.0> iex(2)> pid <- {:rectangle, 3, 5} Area = 15 {:rectangle, 3, 5} iex(3)> pid <- {:circle, 5} {:circle, 5} Area = 78.53981633974483 IEX - INTERACTIVE ELIXIR REPL Friday, September 6, 13
40. defmodule Concurrency do def area_loop do receive do {:die} -> IO.puts “Bye cruel world!” input -> IO.puts Geometry.area(input) area_loop() end end def start do spawn(fn -> Concurrency.area_loop() end) end end defmodule Geometry do def area({ :rectangle, w, h }) do w * h end def area({ :circle, r }) do :math.pi * r * r end def area({ :cone, r, h }) do :math.pi * r * :math.sqrt( r * r + h * h) end end Friday, September 6, 13
41. iex(1)> pid = Concurrency.start #PID<0.48.0> iex(2)> pid <- {:rectangle, 3, 5} 15 {:rectangle, 3, 5} iex(3)> pid <- {:cone, 5, 10} {:cone, 5, 10} 175.62036827601816 iex(3)> pid <- {:die} {:die} Bye cruel World REFACTOR pid = Concurrency.start pid <- {:rectangle, 3, 5} pid <- {:cone, 5, 10} pid <- {:die} Friday, September 6, 13
42. # Tuples - all the way down {:rectangle, 4, 5} # Linked Lists - Yay recursion! [head | tail] # Records - like structs defrecord FileInfo, atime: nil, accesses: 0 # Protocols - for polymorphism defprotocol Blank do @doc "Returns true if data is considered blank/empty" def blank?(data) end # Homoiconic - turtles all the way down Elixir is written in Elixir (esp macros) OTHER GOODIES Friday, September 6, 13
43. LIBRARIES OF NOTE Ruby Elixir Link Rails Dynamo https://github.com/elixir-lang/dynamo Active Record Atlas https://github.com/chrismccord/atlas TestUnit ExUnit http://elixir-lang.org/getting_started/ex_unit/1.html Bundler & Rake Mix http://elixir-lang.org/getting_started/mix/1.html vim-ruby vim-elixir https://github.com/elixir-lang/vim-elixir Friday, September 6, 13
44. MORE READING http://devintorr.es/blog/2013/01/22/the-excitement-of-elixir/ (Comparison) http://learnxinyminutes.com/docs/elixir/ http://benjamintanweihao.github.io/ http://www.unlimitednovelty.com/2011/07/trouble-with-erlang-or-erlang-is- ghetto.html http://www.slideshare.net/Arbow/comparing-cpp-and-erlang-for-motorola- telecoms-software Friday, September 6, 13
45. EVEN MORE READING Friday, September 6, 13
46. LEARN ELIXIR FOR GREAT GOOD Friday, September 6, 13
47. =D THE END Friday, September 6, 13
48. ZANDER HILL TWITTER: @_ZPH ZANDER@CIVET.WS BLOG: CIVET.WS GITHUB: ZPH SOFTWARE ENGINEER AT RENTPATH.COM Friday, September 6, 13
49. UPCOMING BOOK - BECOMING AND LEVELING UP AS A DEVELOPER: FOLLOW @_ZPH ON TWITTER FOR UPDATES :) Friday, September 6, 13