Programming Elixir

Using the Representation As Code

When we extract the internal representation of some code (either via a macro parameter or using quote), we stop Elixir from adding it automatically to the tuples of code it is building during compilation—we’ve effectively created a free-standing island of code. How do we inject that code back into our program’s internal representation?

There are two ways.

The first is our old friend the macro. Just like with a function, the value a macro returns is the last expression evaluated in that macro. That expression is expected to be a fragment of code in Elixir’s internal representation. But Elixir does not return this representation to the code that invoked the macro. Instead it injects the code back into the internal ...