Racket Macros — Hygienic Pattern-Based Metaprogramming

In this tutorial, you will learn about Racket Macros. We cover key concepts, practical examples, and best practices to help you master this topic.

Racket macros transform code at compile time. They're hygienic (variable capture is prevented), pattern-based, and fully integrated into the language.

Pattern Macros

; Simple macro
(define-syntax-rule (twice expr)
  (begin expr expr))

(twice (display "Hi
"))
; Outputs "Hi" twice

; With patterns
(define-syntax-rule (my-when condition body ...)
  (if condition
      (begin body ...)
      (void)))

(my-when (> 3 1)
  (display "Greater
"))