From 759c71e15824b5e0ba63fecbe76f80b1c4565fa2 Mon Sep 17 00:00:00 2001
From: yjqww6 <343519265@qq.com>
Date: Sun, 29 Jul 2018 00:18:40 +0800
Subject: [PATCH] fix a broken pattern-expander example (#2197)

pattern expanders shouldn't use `syntax-protect` on their results, and so they shouldn't use `syntax-rules`
---
 pkgs/racket-doc/syntax/scribblings/parse/patterns.scrbl | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/pkgs/racket-doc/syntax/scribblings/parse/patterns.scrbl b/pkgs/racket-doc/syntax/scribblings/parse/patterns.scrbl
index c2f73a1581..6d01e0cb46 100644
--- a/pkgs/racket-doc/syntax/scribblings/parse/patterns.scrbl
+++ b/pkgs/racket-doc/syntax/scribblings/parse/patterns.scrbl
@@ -1151,9 +1151,10 @@ Returns a @tech{pattern expander} that uses @racket[proc] to transform the patte
 @examples[#:eval the-eval
 (define-syntax ~maybe
   (pattern-expander
-   (syntax-rules ()
-    [(~maybe pat ...)
-     (~optional (~seq pat ...))])))
+   (lambda (stx)
+     (syntax-case stx ()
+       [(~maybe pat ...)
+        #'(~optional (~seq pat ...))]))))
 ]}
 
 @defthing[prop:pattern-expander (struct-type-property/c (-> pattern-expander? (-> syntax? syntax?)))]{