erlang/n2o at knpmeetup 2015

Disclaimer

Marketing

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

HOTCODE13 MAXIM SOKHATSKIY

Hey, did you heard about FP?

My Books

Instant Enlightenment

X = 123

Immutable

No shared memory ParadiseShared memory JavaShared memory and state HELL

Immutable

Message passingWe need MQ

No shared memory

Examples of Apps

Examples of Apps

Examples of Apps

Examples of Apps

Examples of AppsRabbitMQRiak, CouchDB, Hibari, KAI, LeoFS, MnesiaejabberdcowboyWings 3D

Soft realtime

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

QuickSort

Theory

BasisInteger 42 Float 4.2 aka doubleAtom okBinary <<"Erlang-powa">>

Reference #Ref<0.0.0.29>Pid <0.0.42>Port #Port<0.42>Fun #Fun<erl_eval.6.82930912>

Basis 2List [<<42,1,0,90>>, 1, ok]

Tuple {<0.0.16>, 107, 42, ["madness", true]}

we can force lists type and typify turplesnamed tuples =:= records

Pattern MatchingX = 1.

[H | T] = [1, 2, 3, 4].

Y = 2.Y = 3. %% err there

{A, B, C} = {ok, X, [“hello”, “knp”, “symfony”]}

Practice

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

Small stuff on Erlangtail_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.

N2O

DEMO TIME

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 ().

Linkshttps://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/