Compile-time calculation: Difference between revisions

=={{header|Racket}}==

Racket, like most Lisp descendants, allows arbitrary code to be executed at compile-time.

<lang lisp>

#lang racket

;; Import the math library for compile-time

;; Note: included in Racket v5.3.2

(require (for-syntax math))

;; In versions older than v5.3.2, just define the function

;; for compile-time

;;

;; (begin-for-syntax

;; (define (factorial n)

;; (if (zero? n)

;; 1

;; (factorial (- n 1)))))

;; define a macro that calls factorial at compile-time

(define-syntax (fact10 stx)

#`#,(factorial 10))

;; use the macro defined above

(fact10)

</lang>