From 530a3eb5e86a388fbe379e93ee5bb9768a017ff1 Mon Sep 17 00:00:00 2001
From: Matthew Flatt <mflatt@racket-lang.org>
Date: Mon, 25 Jan 2010 13:33:42 +0000
Subject: [PATCH] change R5RS to allow splicing unquote at tail when expression
 is not a list; merge to 4.2.4

svn: r17811
---
 collects/r5rs/main.ss | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/collects/r5rs/main.ss b/collects/r5rs/main.ss
index 6e48ff2b52..6fe8f966fd 100644
--- a/collects/r5rs/main.ss
+++ b/collects/r5rs/main.ss
@@ -209,7 +209,9 @@
                   form)]
                 [((unquote-splicing e) . rest)
                  (if (zero? depth)
-                     #`(mappend e #,(loop #'rest depth))
+                     (if (null? (syntax-e #'rest))
+                         #'e ;; Note: we're not check for a list
+                         #`(mappend e #,(loop #'rest depth)))
                      #`(mcons (mcons 'unquote-splicing
                                      #,(loop #'(e) (sub1 depth)))
                               #,(loop #'rest depth)))]