Our most recent Sep book club has been The Passionate Programmer. One of the things mentioned was taking some third party code and reviewing it.

This is not a new idea. Many people has said the best way to understand the code you write is to understand the good and bad of code written by other people. In addition, reading code in a language you are learning exposes you to functions you might not understand as well as idioms you don’t understand. We had an idea of meeting occasionally over lunch and tackling some code. Here’s kinda what I’m thinking that would look like. Please comment and let me know if there’s something else I’m missing.

With that in mind, I found an article on the Haskell Wiki where they implement a chat server in Haskell.

I’m only posting the code review for the final version. Technically, the final version and my changes to make it compile. There are more about that in the comments. I added my initials, BJB, to the comments I made and if I had to look up an API, I provided a link to where I learned about it.

This chat server has a couple of interesting features. It uses lightweight threading to handle multiple incoming and outgoing IO. It uses channels to communicate across these threads. The forking calls are also used to create separate “loops of control” for each IO channel being handled.

Below are the comments I’ve added to the program.