Write Powerful Rust Macros

2 Declarative macros

This chapter covers

• Writing declarative macros
• Avoiding boilerplate and duplication, implementing newtypes, writing simple domain specific languages, and composing functions
• Understanding the lazy_static crate

We will start this book in easy mode with declarative macros. These macros have a syntax that will immediately remind you of pattern matching, with a combination of matchers and transcribers. The matchers contain what you want to match against; the transcriber has the code you will generate when you find that match. It’s just that simple.

NOTE This chapter’s focus is a broad overview of declarative macros and their usage. This stands in contrast with the rest of this book, where we will focus on specific topics ...