--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/truffle/com.oracle.truffle.sl.test/src/com/oracle/truffle/sl/test/ParsingCachedTest.java	Thu Nov 19 09:51:38 2015 +0100
@@ -0,0 +1,67 @@
+/*
+ * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * The Universal Permissive License (UPL), Version 1.0
+ *
+ * Subject to the condition set forth below, permission is hereby granted to any
+ * person obtaining a copy of this software, associated documentation and/or
+ * data (collectively the "Software"), free of charge and under any and all
+ * copyright rights in the Software, and any and all patent rights owned or
+ * freely licensable by each licensor hereunder covering either (i) the
+ * unmodified Software as contributed to or provided by such licensor, or (ii)
+ * the Larger Works (as defined below), to deal in both
+ *
+ * (a) the Software, and
+ *
+ * (b) any piece of software and/or hardware listed in the lrgrwrks.txt file if
+ * one is included with the Software each a "Larger Work" to which the Software
+ * is contributed by such licensors),
+ *
+ * without restriction, including without limitation the rights to copy, create
+ * derivative works of, display, perform, and distribute the Software and make,
+ * use, sell, offer for sale, import, export, have made, and have sold the
+ * Software and the Larger Work(s), and to sublicense the foregoing rights on
+ * either these or other terms.
+ *
+ * This license is subject to the following condition:
+ *
+ * The above copyright notice and either this complete permission notice or at a
+ * minimum a reference to the UPL must be included in all copies or substantial
+ * portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+package com.oracle.truffle.sl.test;
+
+import com.oracle.truffle.api.source.Source;
+import com.oracle.truffle.api.vm.PolyglotEngine;
+import com.oracle.truffle.sl.SLLanguage;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+import org.junit.Test;
+
+public class ParsingCachedTest {
+
+    @Test
+    public void stepInStepOver() throws Throwable {
+        Source nullSrc = Source.fromText("function main() {}", "yields null").withMimeType("application/x-sl");
+
+        PolyglotEngine engine = PolyglotEngine.newBuilder().build();
+        int cnt = SLLanguage.parsingCount();
+        Object res = engine.eval(nullSrc).get();
+        assertNull("Is null", res);
+        assertEquals("One parsing happened", cnt + 1, SLLanguage.parsingCount());
+
+        Object res2 = engine.eval(nullSrc).get();
+        assertNull("Still null", res2);
+        assertEquals("No more parsing happened", cnt + 1, SLLanguage.parsingCount());
+    }
+
+}

--- a/truffle/com.oracle.truffle.sl/src/com/oracle/truffle/sl/SLLanguage.java	Thu Nov 19 09:40:21 2015 +0100
+++ b/truffle/com.oracle.truffle.sl/src/com/oracle/truffle/sl/SLLanguage.java	Thu Nov 19 09:51:38 2015 +0100
@@ -114,6 +114,8 @@
 import com.oracle.truffle.sl.runtime.SLFunction;
 import com.oracle.truffle.sl.runtime.SLFunctionRegistry;
 import com.oracle.truffle.sl.runtime.SLNull;
+import java.util.Map;
+import java.util.WeakHashMap;
 
 /**
  * SL is a simple language to demonstrate and showcase features of Truffle. The implementation is as
@@ -204,8 +206,12 @@
     public static final String builtinKind = "SL builtin";
     private static List<NodeFactory<? extends SLBuiltinNode>> builtins = Collections.emptyList();
     private static Visualizer visualizer = new SLDefaultVisualizer();
+    private static int parsingCount;
+
+    private final Map<Source, CallTarget> compiled;
 
     private SLLanguage() {
+        compiled = Collections.synchronizedMap(new WeakHashMap<Source, CallTarget>());
     }
 
     public static final SLLanguage INSTANCE = new SLLanguage();
@@ -258,6 +264,10 @@
         reportToolDemos();
     }
 
+    public static int parsingCount() {
+        return parsingCount;
+    }
+
     /**
      * Parse and run the specified SL source. Factored out in a separate method so that it can also
      * be used by the unit test harness.
@@ -415,6 +425,11 @@
 
     @Override
     protected CallTarget parse(Source code, final Node node, String... argumentNames) throws IOException {
+        CallTarget cached = compiled.get(code);
+        if (cached != null) {
+            return cached;
+        }
+        parsingCount++;
         final SLContext c = new SLContext(this);
         final Exception[] failed = {null};
         try {
@@ -455,7 +470,9 @@
                 return null;
             }
         };
-        return Truffle.getRuntime().createCallTarget(rootNode);
+        cached = Truffle.getRuntime().createCallTarget(rootNode);
+        compiled.put(code, cached);
+        return cached;
     }
 
     @Override