From 77d29466c7c8598a04d2f7d0ca0f05b5f3e9f154 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Micha=C5=82=20Marczyk?= <michal.marczyk@gmail.com>
Date: Wed, 6 Jun 2012 06:07:30 +0200
Subject: [PATCH] CLJS-303: fix case so it only evaluates its first argument
 once

---
 src/clj/cljs/core.clj | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/src/clj/cljs/core.clj b/src/clj/cljs/core.clj
index 1220ce1651..d489a16c0d 100644
--- a/src/clj/cljs/core.clj
+++ b/src/clj/cljs/core.clj
@@ -713,10 +713,12 @@
                         (if (seq? test)
                           (reduce #(assoc-test %1 %2 expr) m test)
                           (assoc-test m test expr)))
-                      {} (partition 2 clauses))]
-   `(cond
-     ~@(mapcat (fn [[m c]] `((cljs.core/= ~m ~e) ~c)) pairs)
-     :else ~default)))
+                      {} (partition 2 clauses))
+        esym (gensym)]
+   `(let [~esym ~e]
+      (cond
+        ~@(mapcat (fn [[m c]] `((cljs.core/= ~m ~esym) ~c)) pairs)
+        :else ~default))))
 
 (defmacro try
   "(try expr* catch-clause* finally-clause?)