--- /dev/null	2011-08-08 08:40:49.685541141 -0700
+++ new/src/share/classes/java/util/functions/Mapper.java	2011-08-09 10:55:26.000000000 -0700
@@ -0,0 +1,82 @@
+/*
+ * Copyright (c) 2010, 2011, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package java.util.functions;
+
+/**
+ * Given an input object maps to an appropriate output object. A mapper may
+ * variously provide a mapping between types, object instances or keys and
+ * values or any other form of transformation upon the input.
+ *
+ * <p/>All mapper implementations are expected to:
+ * <ul>
+ *  <li>Provide stable results such that for any {@code t} the result of two
+ * {@code map} operations are always equivalent. ie.<pre>
+ * Foo one = mapper.map(a);
+ * Foo two = mapper.map(a);
+ *
+ * assert one.equals(two) && two.equals(one);
+ * </pre></li>
+ * <li>Equivalent input objects should map to equivalent output objects. ie.<pre>
+ * assert a.equals(b);  // a and b are equivalent
+ *
+ * Foo x = mapper.map(a);
+ * Foo y = mapper.map(b);
+ *
+ * assert x.equals(y); // their mapped results should be as equivalent.
+ * </pre></li>
+ * <li>The mapper should not modify the input object in any way that would
+ * change the mapping.</li>
+ * <li>When used for aggregate operations upon many elements mappers
+ * should not assume that the {@code map} operation will be called upon elements
+ * in any specific order.</li>
+ * </ul>
+ *
+ * @param <T> the type of input objects provided to the {@code map} operation.
+ * @param <U> the type of output objects from {@code map} operation. May be the
+ * same type as {@code <T>}.
+ */
+public interface Mapper<T, U> {
+
+    /**
+     * Map the provided input object to an appropriate output object.
+     *
+     * @param t the input object to be mapped.
+     * @return the mapped output object.
+     */
+    U map(T t);
+
+    /**
+     * Combine with another mapper producing a mapper which preforms both
+     * mappings.
+     *
+     * @param <V> Type of output objects from the combined mapper. May be the
+     * same type as {@code <U>}.
+     * @param after An additional mapping to be applied to the result of this
+     * mapping.
+     * @return A mapper which performs both the original mapping followed by
+     * a second mapping.
+     */
+    public <V> Mapper<T, V> compose(Mapper<? super U, ? extends V> after) default Mappers.chain;
+}