Bits & Sundry

Cloak 1.0.0 Alpha Released!

Mon, 31 Dec 2018 14:58:07 -0800

It’s been a long journey for my Elixir encryption library, Cloak, but we’re finally getting close to a full 1.0.0 release! Since I first published the library on Hex in 2015, both I myself and the community have added: Support for a wide variety of data types Local configuration through Vaults Stronger encryption with AES.GCM support A fully functional key rotation task, using cursors Guides and documentation A 200% performance increase!

Is the Elixir Hype Real?

Mon, 10 Sep 2018 11:33:12 -0700

As I have written previously, I had a burning question I wanted to answer while attending this year’s ElixirConf: “Is Elixir good enough to demand mainstream adoption?” Now that ElixirConf 2018 is behind us, I think the answer is definitely yes. But it’s not for the reasons I expected. My Expectations vs. Reality I adopted Elixir very early on in 2014, because I was bored at my day job and I saw its potential.

ElixirConf 2018 Talk Picks

Wed, 22 Aug 2018 20:05:17 -0700

ElixirConf 2018 is coming up fast, and they’ve announced the schedule, so I thought I’d put together a list of the talks I want to attend and why. I have two goals for this conference: Find out what kinds of projects people are building in Elixir Learn what (if anything) makes Elixir uniquely good for those projects My sense of the Elixir community is that we often use Elixir to build monolithic stateless apps backed by a single database.

Flexible Design with Adapters

Sat, 17 Mar 2018 04:25:00 -0700

With Phoenix 1.3 well behind us now, Elixir developers understand how to approach most problems “The Elixir Way”:

Create a well-named context module for the problem, e.g. “Payment”
Put functions in it, which don’t expose how data is persisted
Profit

Why Your Software Projects Fail

Sat, 30 Sep 2017 00:00:00 +0000

Software projects fail all the time. In fact, if you do client or startup work, you may never yet have built a piece of software that was commercially successful.

Reusable Templates in Phoenix

Tue, 17 Jan 2017 00:00:00 +0000

If you’ve spent any time with React or its look-a-likes, you’ve probably realized that most web apps have a lot of duplication in their templates. This is particularly true of server-rendered apps.

Replace Callbacks with Ecto.Multi

Tue, 27 Sep 2016 00:00:00 +0000

We all have logic in our applications like this:

When a user is created, send a notification to an admin
When a post is deleted, remove it from the search cache
When a password is reset, log out that user’s active sessions

These side effects need to be predictable and reliable. Often, they’re some of the key business logic of the whole application.

Multidimensional Arrays in Elixir

Sat, 23 Apr 2016 00:00:00 +0000

I recently picked up a copy of Game Programming Patterns, and started messing around with implementing some of them in Elixir. I very quickly ran into some trouble dealing with multidimensional arrays.

Background Jobs in Phoenix

Tue, 05 Apr 2016 00:00:00 +0000

In Ruby on Rails, it’s very common to use background worker libraries like Sidekiq to speed up requests and do work asynchronously. Rather than doing all the work that needs to be done inline (and blocking other requests), a background job can speed things up significantly. Sidekiq is great, and you should definitely use it in your Ruby projects.

SEO Tags In Phoenix

Thu, 28 Jan 2016 00:00:00 +0000

Public facing websites need to have some basic search engine optimization (SEO) tags, such as <title> and <meta name="description">. In Rails, you could achieve this pretty simply by putting a yield :head tag in the appropriate layout.

Using GenEvent With Ecto Callbacks

Tue, 08 Dec 2015 00:00:00 +0000

Callbacks. It’s common to write tons of callback methods in Ruby ActiveRecord models, and they’re one reason ActiveRecord models tend to end up so complicated.

Why I'm Checking Out GraphQL

Thu, 15 Oct 2015 00:00:00 +0000

Like many other Elixir programmers, I had heard rumblings about GraphQL, but only recently decided to take a deeper look at it after Chris McCord mentioned it in his recent talk at ElixirConf 2015.

Announcing LearnElixir.tv

Fri, 25 Sep 2015 00:00:00 +0000

Over the past year and a half or so, I have been teaching a programming class. We started out learning the command line and Git, and then moved on to Ruby. In the process, I quickly found out that Ruby isn’t quite as easy to understand as I thought it was.

Cloak Your Ecto Data

Tue, 22 Sep 2015 00:00:00 +0000

I’ve written previously about how to encrypt your data when you are using Ecto, here:

Encrypting Data With Ecto
Changing Your Ecto Encryption Key

After deciding to use encryption for one of my personal projects, I decided that the techniques I wrote about should be built into a Hex package. With that in mind…

Better Pipelines with Monadex

Thu, 03 Sep 2015 00:00:00 +0000

Before I get started, let me be blunt, this is not another monad tutorial. The world has enough of those already. I’m not going to write about functors and applicatives or other technical theory. This is just a post about how a particular monad made my life better. The Problem: Network Requests I’m building a Phoenix app where people can buy something. So, I needed to integrate with my favorite gateway, Stripe, which involves making a series of network requests each time a user makes a purchase.

How to Run Elixir in Cloud9's IDE

Fri, 28 Aug 2015 00:00:00 +0000

Cloud9 is a great web-based development platform. If you don’t have access to a dedicated machine you can set up for development, or if you just prefer to keep all your coding in neat, tiny VMs, Cloud9 could be just what you’re looking for. It’s particularly good for students learning to code. Cloud9 doesn’t provide an Elixir-specific workspace template, so you have to configure one yourself. Here’s how to do that:

GenServers as Concurrent Objects

Fri, 21 Aug 2015 00:00:00 +0000

This is a post for fellow object-oriented developers trying to get their heads around how Elixir/Erlang use processes as a basic abstraction, rather than classes and objects.

Elixir as an Operating System

Mon, 03 Aug 2015 00:00:00 +0000

I recently was using a Synology Diskstation, and I was very impressed by their web admin interface. They have successfully emulated a desktop operating system, complete with downloadable programs, file browsing, and more. You can manage the whole system from the browser in a way that feels very much like Windows 7.

Avoid Long-Lived Feature Branches

Tue, 28 Jul 2015 00:00:00 +0000

Today, I intend to rail against the evils of long-lived feature branches. Having collaborated on a number of projects where they happened, I’m now convinced that they are almost always the wrong way to go.

Fixtures for Ecto

Thu, 16 Jul 2015 00:00:00 +0000

When you test an Elixir app that uses Ecto, you will find yourself needing a way to insert test data into the database. There are many different approaches to doing this, and I thought I’d cover a few, and then describe what I think the best approach is for Elixir.

Changing Your Ecto Encryption Key

Thu, 09 Jul 2015 00:00:00 +0000

Author’s Note: I’ve released an open-source Hex package that implements the approach to encryption I describe in this post. Read the announcement post here.

READ THIS FIRST: Encrypting Data with Ecto

In an earlier post, I wrote about how to encrypt data with Ecto, Elixir’s database library. However, I didn’t cover how to change your encryption key, which you’ll definitely want to do periodically. I want to show how do that in this post.

Encrypting Data With Ecto

Fri, 03 Jul 2015 00:00:00 +0000

Author’s Note: This post has been substantially updated since it was first posted. A much stronger crypto implementation has been used and the code has been reworked to be cleaner and more efficient.

I’ve also released an open-source Hex package that implements the approach to encryption I describe in this post. Read the announcement post here.

In the future, as privacy becomes more and more of an issue, we’re going to be encrypting a lot more of the data we store on the web. With that in mind, I thought it would be a good idea to figure out a good way to integrate data encryption with Elixir’s database library, Ecto.

Rate Limiting a Phoenix API

Tue, 16 Jun 2015 00:00:00 +0000

In my spare time, I’ve been working on a little Phoenix project that involves a JSON API. Developers frequently neglect rate limiting when they build an API, assuming they are even aware that it is a best practice.

It’s true that in many cases rate limiting isn’t worth the effort, but when it comes to authentication, it definitely is. For example, the recent high-profile iCloud security breach which released celebrity photos in to the internet could have been prevented had Apple implemented rate limiting on one of their authentication APIs. This would have prevented the brute-force attack that the hackers used to guess the celebrities’ passwords.

How to Write Guard Macros

Wed, 10 Jun 2015 00:00:00 +0000

I recently discovered that it is possible to write custom guard macros for Elixir, provided that the macro expands to expressions that are supported in guards natively.

I used this to create an is_blank guard. Elixir doesn’t come with a blank? function, so you have to do it manually. Blank values are " ", "", and nil. To check blank? in Elixir, you can check if a given value is in this array of blank values.

Number Helpers For Elixir

Tue, 09 Jun 2015 00:00:00 +0000

Since I started working on a Phoenix app, I was frustrated by the lack of number conversion helpers in Elixir/Erlang. I didn’t want to have to rewrite number_to_currency every time I want to use it.

So, I created Number. It’s basically a shallow clone of NumberHelper from ActionView in Rails. Now, Elixir users can have number_to_currency too!

Useful Ecto Validators

Wed, 20 May 2015 00:00:00 +0000

Over the past week, I’ve created a couple custom validators for my Elixir projects which use Ecto. Since validators are just functions that take a changeset and return a changeset, they’re very easy to write.

Testing Ecto Validations

Fri, 08 May 2015 00:00:00 +0000

I recently was playing around with Phoenix and Ecto, Elixir’s database library, and I wanted to test my validations. In the process, I wrote a little library along the lines of Shoulda from Ruby. However, when José Valim saw it, he suggested a much better approach which I think illustrates what makes Elixir great.

Why a Static Blog is a Good Idea

Tue, 28 Apr 2015 00:00:00 +0000

Rather than use a popular blogging solution like Wordpress, Blogger, or even the new kid on the block, Ghost, I chose to use an old school method to write my blog: plain text.

This blog is a static site. My posts are written in plain text in a text editor on my computer, and are converted into simple HTML pages when I deploy. There is no admin panel. There is no pretty online editor. Just text.

Telephonist: State Machines for Twilio

Thu, 23 Apr 2015 00:00:00 +0000

After a couple months of work, I’ve finally got the library I’ve been working toward for Twilio, and I’m calling it “Telephonist”. You can read all about it over on Github, but here’s a taste:

On Keeping Your ETS Tables Alive

Fri, 17 Apr 2015 00:00:00 +0000

In my ongoing quest to make Elixir libraries that integrate with Twilio, I found that I needed a lookup table to store the state of ongoing calls in.

In Rails, this table would probably be a Postgres table or a list key in Redis. But before jumping to one of these familiar solutions, I thought, “What does Elixir/Erlang already have that would meet this need?”

Build Dialyzer PLTs on Travis CI

Wed, 08 Apr 2015 00:00:00 +0000

In a previous post, I wrote about how to easily get a prebuilt PLT for your Elixir builds on Travis. But what if that doesn’t work for you? What if you have special requirements that my prebuilt PLTs don’t meet?

Run Dialyzer on Elixir on Travis CI

Fri, 03 Apr 2015 00:00:00 +0000

In my last post, I talked about Elixir’s typespec annotations and Erlang’s static analysis tool, Dialyzer. All that talk was great and all, but how do you actually use Dialyzer on Elixir projects?

Contracts: Type Checking for Ruby

Wed, 01 Apr 2015 00:00:00 +0000

Like many Rubyists who read popular coding news, I recently came across the Contracts gem. It caught my eye because it implements some of the features I like in Elixir, but for Ruby.

Stream Paginated APIs in Elixir

Sat, 28 Mar 2015 00:00:00 +0000

_This article was recently featured in Elixir Radar. Since it was written, I’ve found a simpler way to implement this kind of Stream. I’ll be writing an updated tutorial in the future, but if you’re interested, you should also check out the current state of ExTwilio.ResultStream._

This past week, as I worked on my new ExTwilio API library for Twilio, I ran into a snag dealing with Twilio’s API pagination.

Twilio paginates its “list” APIs, requiring multiple requests to fetch all of a given resource. However, users of my API library will expect to be able to fetch all of a resource and perform operations on it, like this:

calls = ExTwilio.Call.all
Enum.each calls, fn(call) ->
  # perform some operation
end

Users won’t want to mess with the details of pagination. They want to get a collection containing everything and then operate on it.

I find that there are two basic ways to achieve this, a blocking way and a non-blocking way.

Manage Environment Variables in Elixir

Sat, 21 Mar 2015 00:00:00 +0000

I love how the Elixir build tool, Mix, has built-in support for configuration settings. It makes configuring packages much simpler by providing a standard interface for config settings.

I’m currently developing a Twilio API client for Elixir. While I develop and test it, I need to store an “Account SID” and “Auth token” to make requests. Naturally, I turned to Mix config.

ExTwiml

Wed, 11 Mar 2015 00:00:00 +0000

At LeadSimple, we use Twilio to handle phone call routing. Twilio interacts with regular HTTP endpoints on your server to control calls and SMS messages, through a form of XML they call TwiML.

I’ve been toying recently ideas on how to bring next-generation Erlang (Elixir) and next-generation telephony (Twilio) together. Toward that end, I made a little library this week to make generating TwiML from Elixir easy.

Thoughts on Immutable Databases

Fri, 06 Mar 2015 00:00:00 +0000

I came across this talk on Apache Samza this past week:

https://www.youtube.com/watch?v=fU9hR3kiOK0

The author, Martin Kleppmann, also wrote up an excellent post on the same subject, which is well worth your time.

In both, he argues that an stream of immutable facts (a log, essentially) is a better datastructure for databases, rather than the existing model of mutating state in place.

Why I Write Straight HTML and JS

Fri, 27 Feb 2015 00:00:00 +0000

It’s very popular in the Rails community to use templating languages that compile down to HTML. The asset pipeline likewise makes it very easy to use Coffeescript and SCSS, or other languages that compile down to Javascript and CSS.

When I got started with Rails, I was just as much a fan of these technologies as everyone else. Over time though, they’ve lost their shine, and I’ll explain why.

Find the Nth Prime in Elixir

Sat, 21 Feb 2015 00:00:00 +0000

I’ve been working through Exercism’s set of code challenges for Elixir, and came across this one.

Write a program that can tell you what the nth prime is.

By listing the first six prime numbers: 2, 3, 5, 7, 11, and 13, we can see that the 6th prime is 13.

This is a perfect use case for Elixir’s Stream module, because we want to generate a list of values and return the last one.

Undo a Commit in Git

Thu, 19 Feb 2015 00:00:00 +0000

I keep forgetting how to do this, so I thought I’d post this for my own future benefit: // Completely deletes the most recent commit $ git reset --hard HEAD~1 // Removes the most recent commit, but leaves changes intact. Useful if you // might want to make a new commit. $ git reset --soft HEAD~1

Think About the Next Guy

Sun, 15 Feb 2015 00:00:00 +0000

I hated all my toil in which I toil under the sun, seeing that I must leave it to the man who will come after me, and who knows whether he will be wise or a fool? Yet he will be master of all for which I toiled and used my wisdom under the sun. - Ecclesiastes 2:18-19

Everyone dies, and the world is constantly changing. Therefore, if anything is to be carried on into the future, there must be a succession. Someone new must take up the mission, the art, or the craft, or it will die with the current generation.

Moving Beyond Ruby

Mon, 09 Feb 2015 00:00:00 +0000

I’ve been a Ruby developer for the last 4 years of my career. It’s served me very well, I still like it, and I expect that I’ll still be writing it for my career for years to come. However, there are some things that Ruby (and Rails) don’t do so well out of the box, and these things are causing me to look elsewhere.

The Spark Notebook

Sat, 07 Feb 2015 00:00:00 +0000

My wife recently backed the Spark Notebook Kickstarter. and she kindly ordered me two of them as a late Christmas present.

So far, I love it. You know how we all make New Year’s Resolutions and then break them? Thanks to this notebook, this is the first year I feel like I have a fighting chance of actually accomplishing my goals.

Yet Another Tech Blog

Sat, 07 Feb 2015 00:00:00 +0000

After a long series of attempts to get my blog up and running, I’ve finally settled on a stack I can be happy with for now: Jekyll on Github pages. It’s secure, doesn’t require me to mess with hosting, and lets me write, which is after all what a blog is all about. I plan to write about my day-to-day experiences with technology, particularly the tech that I’m using or learning.

About Me

Mon, 01 Jan 0001 00:00:00 +0000

I’m a Christian, married to a wonderful woman, and have 3 crazy little kids. Professionally, I’m a full-stack engineer at Infinite Red. Definitely check us out if you need to build some software, especially if it has to do with mobile or web. But please bear in mind that everything on this site is my own, and is not endorsed by any of my employers, past or present.

Projects

Mon, 01 Jan 0001 00:00:00 +0000

Programming Courses I’m passionate about teaching programming, so I created the following courses: LearnElixir.tv Teaches Elixir with step-by-step video tutorials. LearnPhoenix.tv Teaches Phoenix, a popular Elixir web framework with step-by-step video tutorials. Open Source Software Number Number formatting for Elixir ExTwilio Elixir API client for Twilio Cloak Elixir encryption library, compatible with Ecto Immortal Helpers for OTP applications