I attended Clojure/conj this past weekend and I wanted to recollect my notes and thoughts on my experience to share with others who weren’t able to make it.

The Venue

The event was held at the George Washington Masonic Memorial, a landmark structure in Alexandria, Virginia.

Being a VA native, I have seen this building several times while visiting the area, but never been inside. Even if I had, I don’t think I’d imagine that it would be a good spot to host a programming conference, but it was.

There was a single stage with theater seating — the acoustics were great and it seemed to be exactly the right size. Not being able to bring food & drinks (i.e., caffeine) into the theater might have been the only inconvenience, but totally understandable given the significance of the building.

The Talks

Day 1

Stu Halloway – data.fresssian

Stu kicked off the conference by introducing a new data encoding library, data.fressian (pronounced ‘data freshen’), that’s being used in Datomic to efficiently transport data across the wire. It has similar properties to edn, like being language agnostic, self-describing, and extensible, but in a binary format. The library’s designers prioritized effectiveness before efficiency to avoid common idiosyncrasies found in existing (JVM) serialization libraries.

Checkout the clojure implementation and the format’s wiki for more information.

Update: video

Mike Anderson – Enter the Matrix

Mike presented the core.matrix API for matrix and vector operations. At its core, the library is a set of protocols that abstract both fundamental (required) and composite (optional) matrix operations. This allows any of the existing matrix libraries for the JVM to be leveraged. By providing a standard API to build applications and leaving the underlying matrix engine pluggable, you can optimize for your particular use case. Since this is all protocol-based, you could conceivably mix & match them.

core.matrix currently ships with protocol extensions for vectorz-clj, Clatrix and NDArray.

Update: video

Aria Haghighi – Prismatic’s Schema

I was looking forward to this talk about Prismatic’s schema library, as I had seen their introductory blog post and started playing with it on my flight to the conference. Schema, as its name suggests, is a way to describe and validate the shape of your data.

Aria made the point that while it’s certainly possible to infer the shape of data from the source code or convey with a docstrings, it’s time consuming and imprecise even in the most trivial of situations. Schemas provide a clear and concise documentation that is non-intrusive like static type systems can be. He reported noticeable productivity gains at Prismatic from using schema and simple code organizational patterns.

Aside from documentation and validation, he mentioned that schemas can be used for other interesting things, like code generation. Prismatic has been using schema to generate ObjectiveC and Java code for their mobile iOS and Android applications, which they plan to open source in the future.

Update: video

Chris Houser & Jonathan Claggett – Illuminated Macros

Clojure has powerful macro facilities, but they can be hard to debug when something goes wrong. There aren’t many ways for a macro’s author to provide fine-grained error messages or suggested fixes. And aside from macroexpand, macros can be opaque to inspect and understand.

Chouser presented properties of macros and ideas that we can learn from (good parts of) Racket’s macros. And Jonathan demoed seqex, a library for “s-expression regexes.”

He gave examples by describing the syntax for the let macro that provides helpful feedback to users and even generates a colorized, complete syntax specification. It would be really cool to see some of these patterns become popular in Clojure.

Update: video

Nada Amin & William Byrd – From Greek to Clojure!

A talk that was equally entertaining as it was thought-provoking; Nada and Will gave tips on how to approach technical research papers with some live coding using core.logic.

Update: video

Rich Hickey – Harmonikit

Rich took a break from his normal keynote this year to present a “fun” project that he’s been working on. Harmonikit is a musical synthesis system built with core.async, overtone, Supercollider, Lemur and a keyboard controller that I didn’t catch the name of.

As always, Rich did an exemplary job of dissecting & describing the problem domain, choosing the distinct problems he wants to address and modeling a system to do it. This system focused on realistically synthesizing acoustics of harmonic (e.g., stringed, wind) instruments.

I won’t do this project & presentation justice if I continue attempting to describe it, so I’ll spare you (and myself) and let you check out the recording when it is released.

Update: video

Day 2

Carin Meier – Learning to Talk to Machines with Speech Acts

Carin is a great presenter and story teller. She told a story illustrating how computer science can learn from philosophy and vice versa. She did an awesome demo of a flying drone using babar and clj-drone, and of course, now I want a drone.

Update: video

Timothy Baldridge – core.async

Tim skipped talking about the rationale of core.async, which is well documented elsewhere, and jumped right into the usage and mechanics of the library that has recently taken the Clojure & ClojureScript communities by storm. I’ve been using this library in a side-project, yet learned several new things like the size of the threadpool.

Update: video

Michael O’Keefe – Predicting Vehicle Usage with Clojure

Michael is a mechanical engineer by trade who has written several vehicle efficiency simulators in the past, with his most recent being in Clojure. He had helpful graphics of the simulation model and totally awesome original illustrations. It seemed that Clojure’s immutable values and ease of building dataflows via functional composition were significant advantages of this type of system.

Interestingly, he was also the only presenter to use LightTable editor during a demo (AFAIK), which was very easy to follow (one presenter used vim, and the rest used emacs)

Update: video

Tim Ewald – Clojure: Programming with Hand Tools

This was one of the most memorable talks I’ve been to. This wasn’t a Clojure or even programming specific talk. Instead, Tim shed some light on the craft of woodworking, particularly with hand-tools rather than than power-tools. Here are a few of the observations he made that I can remember:

• The less you do, the less you know. Automating a complex process isn’t a bad thing in and of itself, but it can build reliance on machines to do a job; humans begin to lose the skills and appreciation for the task at hand.
• Your tools change the way you perceive the world. This is related to the “if all you have is a hammer, everything begins to look like a nail” lesson. Confirmation bias leads to bad decisions that don’t appear bad on the surface.
• Simpler tools give you a broader perspective. You are closer to your trade when your tools allow you (humans) to create unique items, leaving automation to handle the tasks that never change. Regardless of how archaic hand-tools may seem, it can be impossible to match the level of precision that they provide.

Looking forward to watching the recording of this talk.

Update: video

Day 3

Thomas Kristensen – Propagators in Clojure

Thomas presented propaganda, a library for declarative logic programming with propagators. It provides similar functionality as core.logic, but benefits from a more transparent processing model and has efficiency benefits for numerical problems.

Update: video

Fogus – Zeder: Production Rule Systems in Clojure

Zeder is a production rule system (think OSP5), that Fogus has been building. The syntax was very similar to Datomic’s and looks very powerful. He doesn’t appear to have released the source for it yet, but I did find a gist with an example.

Update: video

Russ Olsen – To the Moon!

Russ gave a vivid recollection of America’s race to the moon in the 60’s and the little and big lessons we can learn from it today. The talk’s theme was centered around one of JFK’s quotes, “We choose to go to the moon, not because it’s easy, but because it’s hard.” As a Millennial, I’ve heard and seen this story in popular culture countless times, but he covered some amazing context & details that most leave out.

Russ is a great speaker and the story was inspirational. Definitely watch this talk when the video is released.

Update: video

Last but Not Least

There were a handful of talks not mentioned here, including some lightning talks. One of which was from Alan Dipert on gherkin, aka bash killer. I also got a kick out of talks by Steve Miner and Amit Rathore.

Update: video

Final Words

Huge thanks to conference organizers, Alex Miller and Lynn Grogan, for your hard work and leadership. I am immensely grateful.

And, of course, thanks to all of the speakers, as well as the sponsors, for making it happen. For me, this has been a real testament to the authenticity of the Clojure community.

Lastly, I wanted to give a big thank you to my employer, Huddler, for sponsoring me to attend this conference (and letting me work in Clojure).

Until next year!