A "Hello World" style lightning talk I prepared for a Hello World of programming languages event at work. The goal was to give a rundown of languages we have been playing with and are interested in, and share an overview of the language. The requirement was to give an overview of the language; where it's weaknesses might lie, as no language is perfect for everything; show FizzBuzz in the presentation to have a baseline, and show off an example of what makes it interesting, which included a demo of the Erlang VM's ability to do live code reloading.

1. Hello, Joe. Hello, Mike;
Hello, Robert.1
A Hello World Style Lighting Talk on Erlang.
1. From Erlang the Movie (https://archive.org/details/ErlangTheMovie)

2. Hello, Erlang.
Erlang and OTP was designed for building
distributed, asynchronous, highly-concurrent, fault
tolerant applications with high availability.

3. Hello, Erlang.
Erlang and OTP was designed for building
distributed, asynchronous, highly-concurrent, fault
tolerant applications with high availability.
#BuzzwordBingo

4. Hello, Telecom.

5. Hello, Telecom.
• 100s of Thousands, if not Millions, of calls
happen at the same time

6. Hello, Telecom.
• 100s of Thousands, if not Millions, of calls
happen at the same time
• Your phone line has to always be available

7. Hello, Telecom.
• 100s of Thousands, if not Millions, of calls
happen at the same time
• Your phone line has to always be available
• My call cannot corrupt your call

8. Hello, Déjà vu

9. Hello, Déjà vu
• Sound Familiar?

10. Hello, Internet!

11. Hello, Failure.

12. Hello, Failure.
• In the Real World things fail. Embrace it.

13. Hello, Failure.
• In the Real World things fail. Embrace it.
• “Let It Crash” philosophy

14. Hello, Failure.
• In the Real World things fail. Embrace it.
• “Let It Crash” philosophy
• Immutability

15. Hello, Failure.
• In the Real World things fail. Embrace it.
• “Let It Crash” philosophy
• Immutability
• No Shared State

16. Hello, Failure.
• In the Real World things fail. Embrace it.
• “Let It Crash” philosophy
• Immutability
• No Shared State
• Isolated Processes Communicate Through Message Passing
(Actor Model)

17. Hello, Failure.
• In the Real World things fail. Embrace it.
• “Let It Crash” philosophy
• Immutability
• No Shared State
• Isolated Processes Communicate Through Message Passing
(Actor Model)
• Supervision Hierarchy

18. Hello, Failure.
• In the Real World things fail. Embrace it.
• “Let It Crash” philosophy
• Immutability
• No Shared State
• Isolated Processes Communicate Through Message Passing
(Actor Model)
• Supervision Hierarchy
• Live code reloading

19. Hello, C10k Problem.

20. Hello, C10k Problem.

21. Hello, C10k Problem.

22. –Alan Kay
I thought of objects being like biological cells
and/or individual
computers on a network, only able to
communicate with messages […].2
Hello, OOP.
2. http://userpage.fu-berlin.de/~ram/pub/pub_jf47ht81Ht/doc_kay_oop_en

23. Hello, “Weaknesses”.

24. Hello, “Weaknesses”.
• No strings as a data type

25. Hello, “Weaknesses”.
• No strings as a data type
• List of Integers or Binary types

26. Hello, “Weaknesses”.
• No strings as a data type
• List of Integers or Binary types
• Not super performant for string manipulation, but good enough for most
scenarios

27. Hello, “Weaknesses”.
• No strings as a data type
• List of Integers or Binary types
• Not super performant for string manipulation, but good enough for most
scenarios
• Not great for GUIs

28. Hello, “Weaknesses”.
• No strings as a data type
• List of Integers or Binary types
• Not super performant for string manipulation, but good enough for most
scenarios
• Not great for GUIs
• Not going to be run on your mobile device;

29. Hello, “Weaknesses”.
• No strings as a data type
• List of Integers or Binary types
• Not super performant for string manipulation, but good enough for most
scenarios
• Not great for GUIs
• Not going to be run on your mobile device;
• but great for you mobile device backend.

30. Hello, “Weaknesses”.
• No strings as a data type
• List of Integers or Binary types
• Not super performant for string manipulation, but good enough for most
scenarios
• Not great for GUIs
• Not going to be run on your mobile device;
• but great for you mobile device backend.
• WhatsApp anyone?

31. Hello, “Weaknesses”.
• No strings as a data type
• List of Integers or Binary types
• Not super performant for string manipulation, but good enough for most
scenarios
• Not great for GUIs
• Not going to be run on your mobile device;
• but great for you mobile device backend.
• WhatsApp anyone?
• Not insanely fast

32. Hello, “Weaknesses”.
• No strings as a data type
• List of Integers or Binary types
• Not super performant for string manipulation, but good enough for most
scenarios
• Not great for GUIs
• Not going to be run on your mobile device;
• but great for you mobile device backend.
• WhatsApp anyone?
• Not insanely fast
• "There's no such thing as fast, only fast enough" ~ Joe Armstrong

33. Hello, FizzBuzz.

34. Hello, fizzbuzz.erl
-module(fizzbuzz).
-export([fizzbuzz/1]).
fizzbuzz(N) ->
Translations = lists:map(fun translate/1, lists:seq(1, N)),
lists:foreach(fun(Item) -> io:format("~s~n", [Item]) end, Translations).
translate(N) when N rem 3 =:= 0 andalso N rem 5 =:= 0 ->
'FizzBuzz';
translate(N) when N rem 3 =:= 0 ->
'Fizz';
translate(N) when N rem 5 =:= 0 ->
'Buzz';
translate(N) ->
integer_to_list(N).

35. Hello, fizzbuzz.ex
defmodule FizzBuzz do
def fizzbuzz(n) do
1..n
|> Enum.map(&translate/1)
|> Enum.join("n")
|> IO.puts
end
def translate(n) when rem(n, 3) == 0 and rem(n, 5) == 0, do: :FizzBuzz
def translate(n) when rem(n, 3) == 0, do: :Fizz
def translate(n) when rem(n, 5) == 0, do: :Buzz
def translate(n), do: n
end

36. Hello, fizzbuzz.lfe
(defmodule fizzbuzz
(export (fizzbuzz 1)))
(defun fizzbuzz (n)
(lists:foreach
(lambda (term) (lfe_io:format "~p~n" `(,term)))
(translate-upto n)))
(defun translate-upto (n)
(let ((numbers (lists:seq 1 n)))
(lists:map
(lambda (n) (translate n (rem n 3) (rem n 5)))
numbers)))
(defun translate
([_ 0 0] 'FizzBuzz)
([_ 0 _] 'Fizz)
([_ _ 0] 'Buzz)
([n _ _] n))

37. Hello, Demo.

38. Hello, Proctor.
• http://www.proctor-it.com
• @stevenproctor
• steven.proctor@gmail.com
• @fngeekery
• http://www.functionalgeekery.com
• @dfwerlang
• http://www.meetup.com/DFW-Erlang-User-Group/
• @planeterlang
• http://www.planeterlang.com