Clacks Interpreter - Going Postal at London Clojure Dojo

At the March 2016 London Clojurians code dojo at uSwitch our group created a Clacks Interpreter in honor of Terry Pratchett, the author of the amazing Discworld series of books (and a few TV shows of those books too).

In the 33rd Discworld novel called Going Postal, messages are sent faster than a speeding horse via the Clacks system. This composes of a series of towers that cross a continent and pass messages on via combinations of lights. Each tower sees a grid of lights from a distant tower and sends the message on to the next tower.

The Clacks system was actually introduced in the 24th Discworld novel called “The Fith Elephant”, however its the “Going Postal” book where we learn the full history of the Clacks system.

We created a Clacks Interpreter that converts any English message into its corresponding clacks signal, based on the Clacks alphabet as defined by the board game of the same name. The board game defines the alphabet as a 2 by 3 grid (although in the Discworld its actually 8 large squares). Naturally, the interpreter also converts the Clacks signal back into an English message too.

The code is available on Github at: https://github.com/liamjtaylor/clacks-messenger and read on for a walk through of how we came up with the solution.

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