Introduction to Erlang

Second part of the first Fun(Lx) meetup: an intro to Erlang.
The slides are numerous due to code examples.

Transcript

1. @funlx #funlx
2. First Fun(Lx) meetup!
4. Why Erlang? concurrent fault tolerant distributed soft real-time (low latency)
5. Where Erlang? - Companies
6. Where Erlang? - OSS Projects
7. Erlang basic sequential concurrent
8. Erlang basic sequential concurrent
9. Erlang - Types 1 % number “Hi!” % string hello % atom F % variable true % boolean <<”1”>> % binary F = fun() -> “hi!” end % function spawn(F) % process
10. Erlang - Data Structures {“João Duarte”, 27} % tuple [1,2,3,hello,“hi”,5] % list % other structures: % sets, proplists, dicts, digraphs, queues
11. Erlang - Modules -module(funlx). -export([first_meetup/1, hi/0]). hi() -> “Hi, Fun(Lx)”. first_meetup(presenters) -> [“Joao”, “Nick”]. funlx.erl
12. Erlang - REPL $ erl Erlang R13B01 (erts-5.7.2) [source] [smp:2:2] [rq:2] [async-threads:0] [hipe] [kernel-poll:false] Eshell V5.7.2 (abort with ^G) 1>
13. Erlang - REPL $ erl .. 1> c(funlx).
14. Erlang - REPL $ erl .. 1> c(funlx). {ok, funlx} 2>
15. Erlang - REPL $ erl .. 1> c(funlx). {ok, funlx} 2> funlx:hi().
16. Erlang - REPL $ erl .. 1> c(funlx). {ok, funlx} 2> funlx:hi(). “Hi Fun(Lx)” 3>
17. Erlang - REPL $ erl .. 1> c(funlx). {ok, funlx} 2> funlx:hi(). “Hi Fun(Lx)” 3> funlx:first_meetup(presenters). [“João”, “Nick”]
18. Erlang basic sequential concurrent
19. Erlang - Immutability > X = 1. 1
20. Erlang - Immutability > X = 1. 1 > X = X + 1. ..
21. Erlang - Immutability > X = 1. 1 > X = X + 1. exception error: no match of right hand side value 2 (╯°□°）╯︵ ┻━┻
22. Erlang - Immutability > X = 1. 1 > X1 = X + 1. 2 ┬─┬ ノ( ゜-゜ノ)
23. Erlang - Immutability When you see “=” Don’t think about assigment Remember that Erlang is declarative “X = 1.” is an assertion. “X = X + 1.” makes no (mathematical) sense!
24. Erlang - Pattern Matching 1> {Var1, “hi”, [1,Var2,3]} = {1, “hi”, [1,2,3]}.
25. Erlang - Pattern Matching 1> {Var1, “hi”, [1,Var2,3]} = {1, “hi”, [1,2,3]}. {1, “hello”, [1,2,3]} 2>
26. Erlang - Pattern Matching 1> {Var1, “hi”, [1,Var2,3]} = {1, “hi”, [1,2,3]}. {1, “hello”, [1,2,3]} 2> Var1. 1 3> Var2. 2
27. Erlang - Pattern Matching > L = [1,2,3,4]. [1,2,3,4] > [1 | [2,3,4]] = L. [1,2,3,4]
28. Erlang - Pattern Matching > L = [1,2,3,4]. [1,2,3,4] > [Head | Tail] = L.
29. Erlang - Pattern Matching > L = [1,2,3,4]. [1,2,3,4] > [Head | Tail] = L. [1,2,3,4] > Head. 1 > Tail. [2,3,4]
30. Erlang - Pattern Matching > L = [1]. [1] > [Head | Tail] = L. [1] > Head. 1 > Tail.
31. Erlang - Pattern Matching > L = [1]. [1] > [Head | Tail] = L. [1] > Head. 1 > Tail. []
32. Erlang - Pattern Matching local_greeting() -> “Olá”.
33. Erlang - Pattern Matching local_greet(Language) -> if Language == portuguese -> “Olá”; Language == english -> “Hi”; Language == russian -> “привет”; true -> “你好” end.
34. Erlang - Pattern Matching local_greet(Language) -> case Language of portuguese -> “Olá”; english -> “Hi”; russian -> “привет”; _ -> “你好” end.
35. Erlang - Pattern Matching local_greet(portuguese) -> “Olá”; local_greet(english) -> “Hi”; local_greet(russian) -> “привет”; local_greet(_) -> “你好”.
36. Erlang - Pattern Matching DbUri = {mysql, {“192.168.1.11”, 3306}, {user, pass}}. get_port(Uri) -> IpPort = element(2, Uri), element(2, IpPort).
37. Erlang - Pattern Matching DbUri = {mysql, {“192.168.1.11”, 3306}, {user, pass}}. get_port({mysql, {_, Port}, _}) -> Port.
38. Erlang - Pattern Matching map(F, []) -> []; map(F, [H|T]) -> [F(H) | map(F, T)].
39. Erlang - Pattern Matching day_period(Hour) when Hour =< 11 -> “a.m.”; day_period(Hour) when Hour >= 12 -> “p.m.”.
40. Erlang basic sequential concurrent
41. Erlang - Processes 1> F = fun() -> timer:sleep(10000) end. #Fun<erl_eval.20.67289768> 2>
42. Erlang - Processes 1> F = fun() -> timer:sleep(10000) end. #Fun<erl_eval.20.67289768> 2> Pid = spawn(F). <0.83.0> 3>
43. Erlang - Processes 1> F = fun() -> timer:sleep(10000) end. #Fun<erl_eval.20.67289768> 2> Pid = spawn(F). <0.83.0> 3> Pid2 = spawn(F). <0.84.0> 4>
44. Erlang - Processes 4> Pid ! “hi”. “hi” 5> exit(Pid, “because I want to”). true 6> erlang:process_info(Pid). undefined 7>
45. Erlang - Processes -module(funlx). -export([do_addition/3, adder/0]). do_addition(Adder, X, Y) -> Adder ! {self(), X, Y}, io:format(“Calculating..~n”), receive Result -> Result end.
46. Erlang - Processes do_addition(Adder, X, Y) -> Adder ! {self(), X, Y}, io:format(“Calculating..~n”), receive Result -> Result end. adder() -> receive {From, X, Y} -> From ! X + Y end.
47. Erlang - Processes 1> c(funlx). {ok, funlx} 2> P = spawn(fun funlx:adder/0). <0.83.0> 3>
48. Erlang - Processes 1> c(funlx). {ok, funlx} 2> P = spawn(fun funlx:adder/0). <0.83.0> 3> funlx:do_addition(P, 10, 32). Calculating.. 42 4>
49. Erlang - Processes 1> c(funlx). {ok, funlx} 2> P = spawn(fun funlx:adder/0). <0.83.0> 3> funlx:do_addition(P, 10, 32). Calculating.. 42 4> funlx:do_addition(P, 10, 32). Calculating.. ???
50. Erlang - Processes 1> c(funlx). {ok, funlx} 2> P = spawn(fun funlx:adder/0). <0.83.0> 3> funlx:do_addition(P, 10, 32). Calculating.. 42 4> funlx:do_addition(P, 10, 32). Calculating.. ⌛
51. Erlang - Processes do_addition(Adder, X, Y) -> Adder ! {self(), X, Y}, io:format(“Calculating..~n”), receive Result -> Result end. adder() -> receive {From, X, Y} -> From ! X + Y end.
52. Erlang - Processes do_addition(Adder, X, Y) -> Adder ! {self(), X, Y}, io:format(“Calculating..~n”), receive Result -> Result end. adder() -> receive {From, X, Y} -> From ! X + Y end, adder().
53. Erlang - Processes 1> c(funlx). {ok, funlx} 2> P = spawn(fun funlx:adder/0). <0.83.0> 3> funlx:do_addition(P, 10, 32). Calculating.. 42 4> funlx:do_addition(P, 1, 3). Calculating.. 4
54. Erlang - Processes do_addition(Adder, X, Y) -> Adder = spawn(fun funlx:adder/0), Adder ! {self(), X, Y}, io:format(“Calculating..~n”), receive Result -> Result end. adder() -> receive {From, X, Y} -> From ! X + Y end.
55. Erlang - Processes 1> c(funlx). {ok, funlx} 2> funlx:do_addition(10, 32). Calculating.. 42 4> funlx:do_addition(1, 3). Calculating.. 4
56. Erlang - Processes 5> funlx:do_addition(1, “hello”).
57. Erlang - Processes 5> funlx:do_addition(1, “hello”). Calculating.. =ERROR REPORT==== 5-Mar-2014::20:24:06 === Error in process <0.83.0> with exit value: {badarith,[{funlx,adder,0,[{file,"funlx. erl"},{line,14}]}]} ⌛
58. Erlang - Processes do_addition(X, Y) -> Adder = spawn_link(fun funlx:adder/0), Adder ! {self(), X, Y}, io:format(“Calculating..~n”), receive Result -> Result end. adder() -> receive {From, X, Y} -> From ! X + Y end.
59. Erlang - Processes 1> c(funlx). {ok, funlx} 2> funlx:do_addition(1, “hello”). Calculating.. =ERROR REPORT==== 5-Mar-2014::20:24:06 === Error in process <0.83.0> with exit value: {badarith,[{funlx,adder,0,[{file," funlx.erl"},{line,14}]}]} 3>
60. Erlang - Processes do_addition(X, Y) -> process_flag(trap_exit, true), Adder = spawn_link(fun funlx:adder/0), Adder ! {self(), X, Y}, io:format(“Calculating..~n”), receive Result -> Result end.
61. Erlang - Processes 1> c(funlx). {ok, funlx} 2> funlx:do_addition(1, “hello”). Calculating.. {'EXIT',<0.41.0>, {badarith,[{funlx,adder,0, [{file,"funlx.erl"},{line,32}]}]}} =ERROR REPORT==== 5-Mar-2014::20:24:06 === Error in process <0.41.0> with exit value: {badarith,[{funlx,adder,0,[{file," funlx.erl"},{line,14}]}]} 3>
62. Erlang - Processes do_addition(X, Y) -> process_flag(trap_exit, true), Adder = spawn_link(fun funlx:adder/0), Adder ! {self(), X, Y}, io:format(“Calculating..~n”), receive {‘EXIT’, _, _} -> error; Result -> Result end.
63. Erlang - Processes 1> c(funlx). {ok, funlx} 2> Result = funlx:do_addition(1, “hello”). Calculating.. error =ERROR REPORT==== 5-Mar-2014::20:24:06 === Error in process <0.41.0> with exit value: {badarith,[{funlx,adder,0,[{file," funlx.erl"},{line,14}]}]} 4> Result. error
64. Erlang - OTP Behaviors Generic patterns built using processes: gen_server gen_fsm supervisor
65. Erlang very cheap isolated processes lightweight message passing immutable data structures pattern matching OTP
66. Erlang - Learn More
67. Erlang - Learn More
68. Erlang - Learn More
69. Erlang - Learn More
70. Questions?