These are initial steps to understanding how to read in data using Clojure. We chose to use a filesystem. However, in the real world, data can come from a web source, e-mail source, data feeds from your financial provider, and so on.

Once data was in your system, we took a look at a few ways of querying it. This included simple filtering, then adding more constraints in a logical OR and AND fashion. Most of these approaches involved first-class function manipulations, which is often the preferred choice. However, if you need a syntax to alter the control flow of a program or control if or when inputs get evaluated, custom syntaxes that are provided by macros are a popular approach in Clojure.

In the final chapter, we'll take all the knowledge we've gained and design buy or sell signals based on our analysis so far.