<< Steps to metal
Which goes, From input state
let a := 2
|> 1. Parsing
Lean Syntax object or commonly known as Concrete Syntax Tree
|> 2. Elaboration
Lean Expr object or commonly known as Abstract Syntax Tree
|> 3. Evaluation
C string or int a = 2;
|> 4. C Compiler
Binary string 0100100
The steps above restate what's written in the image. It's to make them readable.
<< So where are the macros?
Macros, according to the book is just "glorified regular expression" I think what the book is trying to convey is the way in which Syntax objects are created and probably how they are parsed.