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| author | Eli Barzilay <eli@barzilay.org> | 2013-07-16 01:30:51 -0400 |
|---|---|---|
| committer | Eli Barzilay <eli@barzilay.org> | 2013-07-16 01:30:51 -0400 |
| commit | d8989c2ae3d685b15c16491e30ae8d40580ed059 (patch) | |
| tree | 3d873100303fe153e86bc3dc8ccc947123050047 | |
| parent | e8f8e2331bf57da87949cd130d6c21dfcb4862ca (diff) | |
Improve macro definition.
It's more robust to use `let' to have the macro result in its own new
scope. (Unrelated to the hygiene point, of course.)
| -rw-r--r-- | racket.html.markdown | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/racket.html.markdown b/racket.html.markdown index e528bc74..526d008c 100644 --- a/racket.html.markdown +++ b/racket.html.markdown @@ -423,8 +423,7 @@ vec ; => #(1 2 3 4) ;; Macros are hygienic, you cannot clobber existing variables! (define-syntax-rule (swap x y) - (begin - (define tmp x) + (let ([tmp x]) (set! x y) (set! y tmp))) |