An introduction to Elixir. The language. The Platform. From the history of Erlang to Elixir. Why is useful. What are their strengths.

1. A sip of Elixir
@emadb

2. What language is this?

3. Erlang
• 1987 - First version written in Prolog.
Good but slow
• Early ’90 - BEAM
• 1992 - Erlang in production
• In 1998 Ericsson announced the
AXD301 switch, containing over a
million lines of Erlang and reported to
achieve a high availability of nine “9"s.
• 1999 Ericsson banned the use of
Erlang
• 2004 Ericsson lifted the ban

4. Erlang

5. Concurrency Oriented
Programming Languages

6. COP Languages
In languages like <noname> they forgot about concurrency. It either
wasn’t designed in from the beginning or else it was added on as an
afterthought.
Armstrong, 2002

7. COP Languages
• Processes are truly independent
• No penalty for massive parallelism
• No unavoidable penalty for distribution
• Concurrent behaviour of program same on all OSs
• Can deal with failure

8. COP is nice
• The world is parallel
• The world is distributed
• Things fail
• Make more powerful by adding more processors
• Our brain intuitively understand parallelism

9. Erlang is COP

10. Open Telecom Platform
• Delivered with Erlang and written in Erlang, it contains:
• an Erlang interpreter (which is called BEAM)
• an Erlang compiler
• a protocol for communication between servers (nodes)
• An Object Request Broker
• a static analysis tool called Dialyzer
• a distributed database server (Mnesia)
• many other libraries and utilities

12. Elixir
• R&D project form
Plataformatec (2011)
• His goals were to enable
higher extensibility and
productivity in the
Erlang VM while keeping
compatibility with
Erlang's ecosystem

13. Features
• Compiles to bytecode for the BEAM
• Functional language, everything is an expression
• Erlang functions can be called without costs
• Metaprogramming with macros
• Polymorphism via a mechanism called protocols and
behaviours
• Pattern matching
• Expressive language that programmers love (like Ruby!)

14. Elixir today
• Version 1.6.5
• New version every 6 months (1.7 in July)
• Hex package management (~6k packages)
• Vibrant community

15. A tour of the language

16. Processes
• Everything runs in a process
• Process is isolated
• Process communicate using messages
• Inside a process code runs in a single thread

17. GenServer
• The basic behaviour for a general purpose process
• Has state
• A “public interface” (client api vs. server callbacks)
• Callbacks to handle messages and send responses
• Terminate callback

18. GenServer
• init(args) :: {:ok, state}
A sort of “constructor” for the server
• handle_call(request, from, state) ::
{:reply, reply, new_state}
Handle synchronous messages
• handle_cast(request, state) :: {:noreply,
new_state}
Handle asynchronous messages
Redux?

19. GenServer and…
• GenStage: Producer-Consumer pipelines
• GenStatem: Event driven state machine
• Agent: State management

20. Actor model
• GenServer is the basic block for the actor model
• Code inside GenServer is single thread
• GenServer has it’s own message queue
• GenServer can create other Genservers

21. Supervisor
• A process to monitor other processes
• Handle failures and restarts child as needed

22. Supervisor
• Restarting strategy
• :one_for_one - if a child process terminates, only
that process is restarted.
• :one_for_all - if a child process terminates, all other
child processes are terminated and then all child
processes are restarted.
• :rest_for_one - if a child process terminates, the
“rest” of the child processes are terminated. Then the
terminated child process and the rest of the child
processes are restarted.

23. Applications
• Applications are a bundle of sub-application
• Application consists of a manifest
• Dependencies are sub-application
• Usually it starts the main supervisors and the
dependent applications

24. Other gems
• Macros
• Hot code swapping
• Umbrella projects
• Remote debugging and inspection
• Community ❤

25. Tooling
• mix is rake for Elixir
• https://hex.pm is the package registry
• Spec and Dyalizer
• Release with distillery (erts inside…no
prerequisites!)

26. Libraries and
Frameworks

27. Phoenix

28. Ecto

29. Nerves

30. Absinthe

31. Online Multiplayer game
In few lines of Elixir

32. Mars Rovers
Application
RoverSup
rover_1 rover_2 rover_n
WorldMap

33. Is it production ready?

34. FAQ
• Should I learn Erlang to use Elixir?
• Is it fast?
• To spawn or not to spawn?
• Does it run on windows?

35. Thank you