Small presentation of Erlang and N2O web framework, during KNPMeetup 2015 ( https://github.com/5HT/n2o )

2. Disclaimer

3. Marketing

4. FP makes irreversible changes in your
brain, and makes developer better.

5. HOTCODE13
MAXIM SOKHATSKIY

6. Hey, did you heard about FP?

7. My Books

8. Instant Enlightenment

9. X = 123
Immutable

10. No shared memory Paradise
Shared memory Java
Shared memory and state HELL
Immutable

11. Message passing
We need MQ
No shared memory

12. Examples of Apps

13. Examples of Apps

14. Examples of Apps

15. Examples of Apps

16. Examples of Apps
RabbitMQ
Riak, CouchDB, Hibari, KAI, LeoFS, Mnesia
ejabberd
cowboy
Wings 3D

17. Soft realtime

18. qsort([]) -> [];
qsort([x|Xs]) ->
qsort([Y || Y<-Xs, Y <= X]) ++ [x] ++ qsort([Y || Y<-Xs, Y > X]).
QuickSort

19. Theory

20. Basis
Integer 42
Float 4.2 aka double
Atom ok
Binary <<"Erlang-powa">>
Reference #Ref<0.0.0.29>
Pid <0.0.42>
Port #Port<0.42>
Fun #Fun<erl_eval.6.82930912>

21. Basis 2
List [<<42,1,0,90>>, 1, ok]
Tuple {<0.0.16>, 107, 42, ["madness", true]}
we can force lists type and typify turples
named tuples =:= records

22. Pattern Matching
X = 1.
[H | T] = [1, 2, 3, 4].
Y = 2.
Y = 3. %% err there
{A, B, C} = {ok, X, [“hello”, “knp”, “symfony”]}

23. Practice

24. Small stuff on Erlang
fib(0) -> 0;
fib(1) -> 1;
fib(N) -> fib(N - 1) + fib(N - 2).

25. Small stuff on Erlang
tail_fib(N)->
tail_fib_acc(N, 0, 0, 0).
tail_fib_acc(N, Counter, Prev, PrevPrev) ->
case Counter of
N -> Prev + PrevPrev;
0 -> tail_fib(N, Counter + 1, 0, 0);
1 -> tail_fib(N, Counter + 1, 1, 0);
_ -> tail_fib(N, Counter + 1, Prev + PrevPrev, Prev)
end.

26. N2O
DEMO TIME

27. N2O, Idiomatic chat
-module ( chat ).
event (chat) -> wf:send (chat, wf:q (message) ),
body () ->
wf:async ( fun() -> loop() end, chat ),
[ #panel { id=history }, #textbox { id=message },
#button { postback=chat } ].
loop () ->
receive Message ->
wf:insert_bottom ( history, #span { text=Message } ),
wf:flush () end, loop ().

28. Links
https://github.com/5HT/n2o
http://slides.com/maximsokhatsky/n2o
https://www.youtube.com/watch?v=FKPJ3C-UZJw
https://github.com/synrc/kvs
https://synrc.com/