Clojure Conj 2013

Clojure Conj 2013 venue small 2Last week I attended Clojure Conj, the annual “main” event for the Clojure development community. Past events were held in Durham, NC at a typical conference hotel; this year’s event was held in Alexandria VA, in the much more impressive venue shown here – I happened to look out my hotel room window at just the right moment, as you can see.

(I should mention of course, that Oasis Digital was a sponsor.)

As is often the case that software related conferences, it is not so much about the learning (which you can achieve as well or better on the Internet) as about the community. Some of my current attention is on ClojureScript; I’ve been interacting with the group of people on its mailing list, but last week I have the opportunity to chat with several them in person.

Here is an overall impression. Most of the content was very worthwhile. Many of the talks were at a relatively sophisticated technical level, which is very good for the audience at this event, mostly populated by people who are already in the Clojure world.

A few of the talks, which I will not identify out of politeness, were not so hot in terms of the value received versus the hour spent watching. My hope is that as the community grows and matures, there will be a greater supply of speakers who are more skilled at reliably delivering value in the time allotted – It would be great to raise that evaluation from “most of the talks were worth the time” to “all of the talks were worth the time”.

A few more specific notes:


Fressian is near to my heart because my previous company (which sold a Java Web Start SaaS application) used Hessian, after which Fressian is modeled and named. Hessian served us very well, and we were able to adjust its source code a bit too match a specific local need to traverse some object references and not others.

Prismatic Schema

Prismatic Schema is a very appealing piece of technology, which will quite likely make it into my projects.

Clojure Conj 2013 venue small 3


I get the impression that Rich Hickey can spend a relatively small number of hours and come up with yet another fascinator chunk of technology. Perhaps “on-demand”. Or even without any demand, just sitting in a hammock.

The most visually appealing part of the project was an off-the-shelf $50 product for building audio control GUIs on iPads. A talk about how to make things like (in Clojure, if at Clojure Conj) hat might be even more interesting than this talk which merely used it.

Programming with Hand Tools

Tim Ewald is an outstanding speaker. His talk about hand tools was a delight, partly because I spend many hours as a teen working on projects in wood, with a combination of hand tools and power tools. But I came away with a somewhat different impression than Tim did about the relative merits of power tools versus hand tools. This is probably an indication of my lack of skill, but I was always much happier with the results I could get with a power tool. A carefully used power tool could produce a bit of work perfectly straight, perfectly cut, etc. the first time. I remember in a required (!)¬†shop class at school (do they even have those anymore?) cutting a dado with a hand saw and chisel. Neither my cut, nor any other, not the teacher’s, was anywhere near the ideal easily obtained with a table saw and dado blade.

Still, that didn’t take away from the enjoyment of Tim’s talk at all. I think this is a talk people will mention at every future Clojure Conj to come.


Clojure(Script) for Server and Client Development

ClojureScript is a relatively recent addition to the list of languages which compile to JavaScript. Unlike some such languages, it does not only fix the minor difficulties with JavaScript (like syntax oddities), rather it is a wholly different language with a LISP-like syntax and very powerful semantics. Many words have been written on “why ClojureScript”, which I won’t attempt to restate here. Rather, these are the handful of reasons ClojureScript is worthy of a deep dive for projects like ours (at work).

Strengths (for us)

  • It is a “programmable programming language”, especially good for building abstractions – the usual LISP strength.
  • It is biased toward immutability and functional style (though many things are mutable, because of JavaScript underneath); yet can easily escape when pragmatically needed.
  • Is it is possible to use the same(-ish) language on the client and server; our projects benefitted from this for years in the boring old days of desktop client-server development.
  • Client side ClojureScript is built on JavaScript runtimes and libraries: proven, strong, dominant, multiplatform.
  • Server side Clojure is built on Java runtimes and libraries: proven, strong, dominant, multiplatform.
  • Although there are not a great number of ClojureScript developers, they tend to be good developers.


  • Although parentheses-first syntax does not bother me, it does bother some developers.
  • ClojureScript is different enough from JavaScript that knowledge of the latter doesn’t help much with the former;
  • Yet, it is still necessary to know JavaScript well.
  • There are at least 100x fewer ClojureScript developers than JavaScript developers; perhaps 1000x.
  • Fits well with some JS libraries, less well with others – sometimes that prevents the “shove in an hack” style of development which is JavaScript’s strength and weakness.