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diff --git a/src/clojure/contrib/core.clj b/src/clojure/contrib/core.clj
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+;   Copyright (c) Laurent Petit and others, March 2009. All rights reserved.
+
+;   The use and distribution terms for this software are covered by the
+;   Eclipse Public License 1.0 (http://opensource.org/licenses/eclipse-1.0.php)
+;   which can be found in the file epl-v10.html at the root of this 
+;   distribution.
+;   By using this software in any fashion, you are agreeing to be bound by
+;   the terms of this license.
+;   You must not remove this notice, or any other, from this software.
+
+;; functions/macros variants of the ones that can be found in clojure.core
+
+;; note to other contrib members: feel free to add to this lib
+
+(ns clojure.contrib.core
+  (:use clojure.contrib.def))
+
+(defmacro- defnilsafe [docstring non-safe-name nil-safe-name]
+  `(defmacro ~nil-safe-name ~docstring
+     {:arglists '([~'x ~'form] [~'x ~'form ~'& ~'forms])}
+	   ([x# form#]
+	     `(let [~'i# ~x#] (when-not (nil? ~'i#) (~'~non-safe-name ~'i# ~form#))))
+  	 ([x# form# & more#]
+	     `(~'~nil-safe-name (~'~nil-safe-name ~x# ~form#) ~@more#))))
+       
+(defnilsafe 
+  "Same as clojure.core/-> but returns nil as soon as the threaded value is nil itself (thus short-circuiting any pending computation).
+   Examples :
+   (-?> \"foo\" .toUpperCase (.substring 1)) returns \"OO\"
+   (-?> nil .toUpperCase (.substring 1)) returns nil
+   "
+   -> -?>)
+    
+(defnilsafe 
+  "Same as clojure.core/.. but returns nil as soon as the threaded value is nil itself (thus short-circuiting any pending computation).
+   Examples :
+   (.?. \"foo\" .toUpperCase (.substring 1)) returns \"OO\"
+   (.?. nil .toUpperCase (.substring 1)) returns nil
+   "
+   .. .?.)