Clojure Hack Night Monday, in Reston

The Capital Area Clojure Users’ Group is hosting an evening of collaborative Clojure coding next Monday, August 2, at 6PM, at Near Infinity, in Reston. Details are available at the group’s meetup page.

Some very experienced people will be on hand, as well as newcomers. We’ll spend some time at the beginning answering questions and helping people with their setups as necessary. (Emacs FTW!) Then it’s on to pair programming. Possible coding projects are listed on the group’s meetup page. More ideas are welcome. There’s a lot of open source Clojure code that needs writing.

Please be sure to sign up through meetup if you’d like to come: spaces are limited.

Announcing Vijual, a graph layout tool

Group member Conrad Barski has just released version 0.1.0 of Vijual, a graph layout engine written in Clojure. Check Conrad’s detailed announcement for lots of information about installation and use. One detail that caught my eye is the use of the leiningen build tool and clojars community repository to package and distribute Vijual. This looks like an emerging standard.

The Joy of Michael Fogus

Here are two pieces of information related to group member Michael Fogus. First, he will be speaking later today, January 14, at FGM in Reston, on the subject of Clojure 1.1 features. More info is at the Capital Area Clojure Users Group meetup site. Second, the book he is co-authoring with Chris Houser, The Joy of Clojure, is available for pre-ordering, and when you pre-order you may read the book as it progresses.

Congratulations, fogus!

Clojure at DC’s ALT.NET, January 27, 7PM

Group member Craig Andera is speaking about Clojure at this month’s ALT.NET meeting. It’s being held at the Motley Fool’s offices in Alexandria, 5 minutes from the Metro stop, on Wednesday, January 27, at 7pm.

Sign up here (it’s free): http://www.eventbrite.com/event/528348304

From the event’s description:

So, what is Clojure?

C# has been adding exciting new features with every release, but many of these have been available in other languages for years or even decades. By examining some of the features of these other languages, we can hope to glean what’s in store for the future of C#. Clojure is a JVM-based Lisp with an integral and interesting approach to concurrency. In this talk, we’ll examine those features, after a brief introduction to Clojure syntax.

Who is Craig?

Craig Andera … is an independent consultant with Wangdera Corporation, where he holds the rank of Jedi Master. He focuses on the design and implementation of large-scale, web-based systems.

A bit of Clojure at RubyNation 2009

Just a quick post to mention how Clojure was mentioned at the RubyNation conference in Reston last weekend.

I gave a lightning talk on day 2. Slides are posted. I only had 6 minutes, so I kept it brief. I don’t think I convinced a lot of the audience members to try it out. Afterwards, though, I got to talk to Aaron Bedra of Relevance, who was a technical editor for Stu’s book. He reports Clojure is actually in use on commercial projects. He’s a swell fellow.

Russ Olsen gave an impromptu talk at the end of the day about Clojure, Scala, Erlang, and Reia. Two things struck me about his approach to new languages. First, he gives a lot of important to “curb appeal”, or how nice the code looks. The parentheses bother him about Clojure and other lisps, same old story. The second thing, though, is the importance given to metaprogramming, which Ruby has brought into the forefront of a lot of developers’ minds. As Russ pointed out, any Lisp makes metaprogramming easy. So that may be a selling point for Clojure among Rubyists.

Meeting Recap, Next Meeting, and Group Projects

The Study Group met on February 21st at 1PM at HacDC’s workshop to continue our discussion of concurrency.

We worked through Stuart Halloway’s snake program, taking note of the way he organized his program by separating the functions that dealt only with immutable data from the ones that dealt with changes in state. We noted his use of “update-” at the beginning of his names for the state-aware functions, and we agreed this was a pretty good convention for functions that were going to update the state of some refs, agents, or atoms. We also paid a fair amount of attention to his consistent use of destructuring as well as the syntax for the alter function. Finally, we looked at Halloway’s atom-snake, which actually stores the state of the entire snake game in an atom and updates it with swap!, and in so doing creates a transaction-free version of the game. This precipitated a discussion of Software Transactional Memory, which allows copies of complex objects, such as the state of a snake game, to be made without duplicating data from original to copy.

Our next meeting is March 14th, at 1PM, at HacDC’s workshop in St. Stephen’s Church in Washington DC. Homework: chapters 5 and 7 (on Functional Programming and Macros) from Stuart Halloway’s Programming Clojure. We hope to see you there.

We’re also starting to consider our capstone project. Watch the Google group for discussions about the project.

Next Meeting: February 21st, 1PM

We’ll be continuing our exploration of concurrency this Saturday at HacDC’s workshop at St. Stephen’s Church, in Northwest DC.

Be sure to check out chapter 6 of Stuart Halloway’s Programming Clojure. It’s the concurrency chapter, and it has some good new stuff in it, including a discussion of atoms and a Clojure snake game that Halloway walks you through fn by fn.

Come with ideas for hacking. I think it might be fun to alter the snake game so you can play against 1+ AI snakes, trying to get those apples. Collisions could eliminate players: think Tron and those light cycles.

Thanks to Serge and HacDC for providing a warm wi-fi-enabled meatspace where we can gather.

Next meeting rescheduled to Saturday January 31st

We will still meet at St. Stephens, in northwest DC, just a week later than we’d initially planned: on the 31st at 1PM, a day before Paul Barry’s beloved Baltimore Ravens take the field in Superbowl 0x2B.

Concurrency is still on the agenda. Watch for an update to the Programming Clojure PDF soon: Stuart Halloway has pledged to try to get us a more complete Concurrency chapter with a discussion of atoms. Thanks, Stuart!

If the door is locked on the 31st, we’ll post a note with my cell phone number for you to call for entry. I hope to see you there.

Next: Concurrency on January 24th, 1PM

** Update: Meeting is rescheduled to Saturday, January 31st, 1PM, at St. Stephens Church. **

Thanks again, everyone, for a great meeting on the 3rd of January. Our next meeting will take place on Saturday the 24th at 1PM in the same location as last time, St. Stephen’s Church at 1525 Newton St NW. We’ll be discussing concurrency.

Your homework for the meeting is the Concurrency chapter in Programming Clojure. Give yourself plenty of time for this text: unless you are familiar with concurrency already, you will probably find this chapter challenging. Concurrency is what Clojure is all about, though, so press on!

Also, please think about little projects or exercises we could undertake in small groups to try out what we’ve learned. Last time we considered card games and exercises from other Lispy textbooks before tackling the Swing app. These might be good ideas again. What kind of concurrent situations come up in software or in real life?

If you haven’t joined us yet or would like to, feel free! We’re still in our tutorial/mentoring
phase, and the environment is welcoming and helpful to novices. If you’re already experienced with Clojure or similar technologies, we’d love to have you join us too.

See you on the 24th.

Next meeting: Saturday, January 3, at 1pm

Our second face-to-face meeting will be held in the auditorium at St. Stephen’s church in Washington, DC. This is a frequent meeting place of HacDC. Thanks to Serge Wroclawski for hooking us up with a great space. The address is 1525 Newton St NW, near the intersection of 16th St NW and Newton. Here is a Google map provided by HacDC showing the church’s location and a path from the Columbia Heights green line Metro station.

Homework

All members are asked to complete the following before our next meeting:

1. Get up and running with an editing environment you feel comfortable with. Emacs is the classic choice, though it isn’t the only option. Look for more on Emacs/SLIME and other editors on this blog, and in the study group mailing list.
2. Read the Preface and the first four chapters of Programming Clojure. (That means, up to and including “Unifying Data with Sequences”.) A new PDF beta version was just released that takes recent changes in Clojure’s syntax into account.
3. Come up with at least one idea for a coding exercise you would like to take part in at the meeting. We’re going to break into small groups and hack some Clojure. Think of tasks that would take about 20 to 30 minutes and that explore some of the ideas in the reading.

I hope to see you on the 3rd.