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diff --git a/sca-cpp/branches/cpp-contrib/kernel/tree.hpp b/sca-cpp/branches/cpp-contrib/kernel/tree.hpp
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+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+/* $Rev$ $Date$ */
+
+#ifndef tuscany_tree_hpp
+#define tuscany_tree_hpp
+
+/**
+ * Functions to work with trees.
+ */
+
+#include "stream.hpp"
+#include "string.hpp"
+#include "function.hpp"
+#include "list.hpp"
+#include "monad.hpp"
+#include "value.hpp"
+
+namespace tuscany {
+
+/**
+ * Make a tree from a leaf and two branches.
+ */
+template<typename T> const list<T> mktree(const T& e, const list<T>& left, const list<T>& right) {
+    return mklist<T>(e, left, right);
+}
+
+/**
+ * Find a leaf with the given key in a tree.
+ */
+template<typename T> const list<T> assoctree(const T& k, const list<T>& tree) {
+    if (isNil(tree))
+        return tree;
+    if (k == car<T>(car(tree)))
+        return car(tree);
+    if (k < car<T>(car(tree)))
+        return assoctree<T>(k, cadr(tree));
+    return assoctree<T>(k, caddr(tree));
+}
+
+/**
+ * Construct a new tree from a leaf and a tree.
+ */
+template<typename T> const list<T> constree(const T& e, const list<T>& tree) {
+    if (isNil(tree))
+        return mktree(e, list<T>(), list<T>());
+    if (e == car(tree))
+        return tree;
+    if (e < car(tree))
+        return mktree<T>(car(tree), constree<T>(e, cadr(tree)), caddr(tree));
+    return mktree<T>(car(tree), cadr(tree), constree<T>(e, caddr(tree)));
+}
+
+/**
+ * Make a tree from an unordered list of leaves.
+ */
+template<typename T> const list<T> mktree(const list<T>& l) {
+    if (isNil(l))
+        return l;
+    return constree(car(l), mktree(cdr(l)));
+}
+
+/**
+ * Convert a tree to an ordered list of leaves.
+ */
+template<typename T> const list<T> flatten(const list<T>& tree) {
+    if (isNil(tree))
+        return tree;
+    return append<T>(flatten<T>(cadr(tree)), cons<T>(car(tree), flatten<T>(caddr(tree))));
+}
+
+/**
+ * Sort a list.
+ */
+template<typename T> const list<T> sort(const list<T>& l) {
+    return flatten(mktree(l));
+}
+
+/**
+ * Make a balanced tree from an ordered list of leaves.
+ */
+template<typename T> const list<T> btreeHelper(const list<T>& elements, const int n) {
+    if (n == 0)
+        return cons<T>(list<T>(), elements);
+    const int leftSize = (n - 1) / 2; {
+        const list<T> leftResult = btreeHelper<T>(elements, leftSize); {
+            const list<T> leftTree = car(leftResult);
+            const list<T> nonLeftElements = cdr(leftResult);
+            const int rightSize = n - (leftSize + 1); {
+                const T thisEntry = car(nonLeftElements);
+                const list<T> rightResult = btreeHelper<T>(cdr(nonLeftElements), rightSize); {
+                    const list<T> rightTree = car(rightResult);
+                    const list<T> remainingElements = cdr(rightResult); {
+                        return cons<T>(mktree<T>(thisEntry, leftTree, rightTree), remainingElements);
+                    }
+                }
+            }
+        }
+    }
+}
+
+template<typename T> const list<T> mkbtree(const list<T>& elements) {
+    return car(btreeHelper<T>(elements, length(elements)));
+}
+
+}
+
+#endif /* tuscany_tree_hpp */