Elixir

Do we just follow the hype? 

Background

  • 1.5 year maintaining a legacy Java web application
  • 1.5 year creating a Ruby web application
  • 3 years maintaining legacy Ruby web applications

Most of my experiences are about working with old and crappy systems

Painful parts

Mutability​/IMpurity

  • You can reopen classes
  • You can include modules
  • You can define callbacks
  • Static variables

Hard to follow / resonate about code. Older the system, worse it is.

Painful parts

Concurrency (lack of)

  • Ruby is slow
  • It's a pain to manage threads
  • Usage of background jobs as a workaround

We more and more need to talk with different APIs to find the best result for the customer.

It's really hard to do it in a safe and concurrent way.

Painful parts

ActiveRecord (ORM)

  • High coupling between business and DB
  • DB queries/commands triggered implicitly
  • Slow tests

Database available everywhere

Solutions?

Golang​

+ concurrency

+ speed

Wasn't convinced at all. It was really fast but all the rest: code, community mindset, Go principles didn't match with me

 - code readability

 - lack of generics

Solutions?

Erlang​

+ concurrency

+ speed

+ immutability

Was totally convinced but I tried to read some book and no way to understand how it really worked / how to use it

 - syntax

 - learning curve

Solutions?

Elixir​

+  concurrency

+  speed

+  immutability

Was really convinced but was a bit worried about the fact it was really young.

+  syntax

±  learning curve

± really young

Erlang

History​

  • Old language (1986)
  • Created by Ericsson
  • Aim of improving the development of telephony applications
  • Functional
  • Concurrent
  • Distributed
  • Fault-Tolerant

Erlang

Functional

  • Immutability
  • Pattern-Matching
-module(fact).
-export([fac/1]).

fac(0) -> 1;
fac(N) when N > 0, is_integer(N) -> N * fac(N-1).

Erlang

Concurrent

  • Actor model
    • The language name them Process
    • Each process has a state
    • Each process can receive messages
    • Each process can reply to messages
    • Process has to be known to be accessible

Erlang

Distributed

  • Each Erlang system running is called a node
  • Connection between node is down on first call 
  • Messages between nodes are transparent

Erlang

Fault-tolerant

  • Supervision tree
    • Tree containing supervisors and workers
    • Workers are processes, they do the work
    • Supervisors monitor workers health
    • Supervisors decide the restart strategy when a worker die

Erlang

Fault-tolerant

S1

S2

S3

S4

S5

P1

P2

P3

P4

Erlang

Why is it still so confidential?

  • Steep learning curve
    • Different way of reasoning about our apps
    • Documentation lightweight
    • Community not easily reachable as beginner
  • Not a lot of communications
  • Syntax hard to understand for most developers

Elixir

History​

  • New language (2012)
  • Created by José Valim
  • Based on the ErlangVM
  • Aim of adding a different language construct
  • Aim of having an excellent tooling
  • Aim of having accessible documentation

Elixir

Erlang Virtual Machine

  • Elixir is a language running on the Erlang VM
  • It can interoperate with Erlang packages easily
  • It gives access, for free, access to all the Actor & Supervision tree

Elixir

Syntax

Erlang syntax was one of the tedious part for most of the developers .

 

Elixir brings a more conventional syntax, looking a lot like Ruby

defmodule Fact do
  def fact(0), do: 1
  def fact(n) when n > 0 and is_integer(n) do
    n * fact(n - 1)
  end
end

Elixir

Features

  • Macros: most of the language is built on top of it
  • Protocols: a bit like an interface 
  • Doctests: doc examples are executable
  • Mix: a task runner, everything use it
  • Resources: Lot of documentation, starter guides and books

Elixir

Why people use it instead of Erlang?

  • Power of the Erlang VM
  • Syntax easier to grasp than Erlang for most devs
  • Learning curve
    • Good documentation (language & packages)
    • Good starter guides (explained in a way people not familiar with functional programming can understand)
    • Books with concrete web examples
  • Communication (blog posts, conferences, books)
  • Community (lot of friendly people on Slack and IRC)

Phoenix

What are the promises?

  • Web framework
  • Fast
  • Strong focus on maintainability 
  • Decoupling of business logic and storage
  • Powerful pipeline of middleware
  • Easy communication through Channels (JS, iOS, ...)

Conclusion

  • Technology built for concurrency, fault-tolerance
  • New/Easier syntax for a battle proved technology (beneficing of years of apps running in production: WhatsApp, Text messages,...)
  • Some new features added on top of Erlang (protocol, macros)
  • Full interoperability with other languages (Erlang, LFE)

Elixir - Do we just follow the hype?

By Kevin Disneur

Elixir - Do we just follow the hype?

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