From d97565efa1c220790716a14e7eb74365c358bf24 Mon Sep 17 00:00:00 2001 From: Eli Barzilay Date: Tue, 16 Jul 2013 04:17:43 -0400 Subject: Quick bad-macro example. --- racket.html.markdown | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/racket.html.markdown b/racket.html.markdown index eb2bf4c0..e894552c 100644 --- a/racket.html.markdown +++ b/racket.html.markdown @@ -353,7 +353,7 @@ m ; => '#hash((b . 2) (a . 1) (c . 3)) <-- no `d' (for ([i (in-range 5 10)]) (printf "i=~a\n" i)) ; => i=5, i=6, ... -;;; Other Sequences +;;; Iteration Over Other Sequences ;; `for' allows iteration over many other kinds of sequences: ;; lists, vectors, strings, sets, hash tables, etc... @@ -557,6 +557,14 @@ vec ; => #(1 2 3 4) (swap! a b) (printf "tmp = ~a; a = ~a; b = ~a\n" tmp a b) ; tmp is unaffected +;; But the are still code transformations, for example: +(define-syntax-rule (bad-while condition body ...) + (when condition + body ... + (bad-while condition body ...))) +;; this macro is broken: it generates infinite code, if you try to use +;; it, the compiler will get in an infinite loop + ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ;; 10. Contracts ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; -- cgit v1.2.3