Meeting Recap, Next Meeting, and Group Projects

February 22, 2009

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

February 17, 2009

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

January 10, 2009

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 meeting: Saturday, January 3, at 1pm

December 10, 2008

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.


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.