Mastering Clojure Macros

Transforming Code

Now you have this sort of abstract idea that you can view code in two different ways: either as code or as data. But what does that mean concretely?

Let’s put this in terms you already know by thinking about the first two phases of the REPL (Read-Eval-Print loop, remember?). The first phase, read, takes a character-based representation (typically an input stream), and turns it into Clojure data structures. So the output of the read phase is data, which is then interpreted by the second phase, eval, as code! Let’s take a closer look so you’ll understand how to transform the code-as-data from the reader into the data-as-code that will be evaluated.

read is a convenient way for us to build the expressions that macros will eventually ...