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Notes on Scala and Elixir - a talk by Jeff Alexander at Erlang&Elixir SF MeetUp (8-Jun-2016)

Jeff uses mostly Scala at work, trying out Elixir mostly for personal education.

Both languages are VM based. Scala: everything is a function. Elixir: everything is an expression. Both have tail recursion and pattern matching.

Let's look at performance:

Build Server

Go to Digital Ocean
Create new ubuntu droplet

Setup Server

My Elixir Deployment Wishlist

Foreward

Based on my recent experience of deployment, I've become rather frustrated with the deployment tooling in Elixir. This document is the result of me thinking to myself, "I wish we had x...". This document isn't meant to dishearten anyone who has built tooling for elixir - thank you so much for what you've done. This is meant more as what I personally see as something that would help a lot of Erlang/Elixir newbies like myself to be able to get deploying quickly and efficiently.

1. Release files should be templates

It should be possible to add in custom configuration to the bootstrap scripts. This would allow plugins to be able to add extra steps to the startup / shutdown / upgrade procedure. One way to implement this would be to make all scripts which handle bootstrapping or controlling the machine [.eex][1] templates. This would allow other parts of the release system to inject new functionality where needed.

Should be work with 0.18

Destructuring(or pattern matching) is a way used to extract data from a data structure(tuple, list, record) that mirros the construction. Compare to other languages, Elm support much less destructuring but let's see what it got !

Tuple

myTuple = ("A", "B", "C")
myNestedTuple = ("A", "B", "C", ("X", "Y", "Z"))

Video stabilization using VidStab and FFMPEG

Examples here use the default settings, see the VidStab readme on GitHub for more advanced instructions.

Here's an example video I made

Install ffmpeg with the vidstab plugin from homebrew

brew install ffmpeg --with-libvidstab

Deploying Phoenix on Dokku

Worked 2015-09-08 for Phoenix 1.0.1 on Dokku 0.3.25.

These instructions assume you've set up Dokku. If not, go find a tutorial for that part. My notes for setting it up on Digital Ocean.

On your local machine, in the app's repo

Create a Dokku app:

My notes for Dokku on Digital Ocean.

These may be a bit outdated: Since I originally wrote them, I've reinstalled on a newer Dokku and may not have updated every section below.

Commands

Install dokku-cli (gem install dokku-cli) for a more Heroku-like CLI experience (dokku config:set FOO=bar).

# List/run commands when not on Dokku server (assuming a "henroku" ~/.ssh/config alias)

ssh henroku dokku

Comparative Benchmark Numbers @ Rackspace

I've taken the benchmarks from Matthew Rothenberg's phoenix-showdown, updated Phoenix to 0.13.1 and ran the tests on the most powerful machines available at Rackspace.

Results

Framework	Throughput (req/s)	Latency (ms)	Consistency (σ ms)

	object Main extends App {
	AvoidLosingGenericType.run()
	AvoidMatchingOnGenericTypeParams.run()
	TypeableExample.run()
	TypeTagExample.run()
	}

	class Funky[A, B](val foo: A, val bar: B) {
	override def toString: String = s"Funky($foo, $bar)"
	}