diff --git a/pom.xml b/pom.xml
index 1833bb1..36acf9c 100644
--- a/pom.xml
+++ b/pom.xml
@@ -9,6 +9,16 @@
   <version>1.0-SNAPSHOT</version>
 
 
+  <dependencies>
+    <dependency>
+      <groupId>org.derive4j</groupId>
+      <artifactId>derive4j</artifactId>
+      <version>0.7</version>
+      <!-- compile-only dependency (not used at runtime):  -->
+      <optional>true</optional>
+    </dependency>
+  </dependencies>
+
   <build>
     <plugins>
       <plugin>
diff --git a/src/main/java/org/mfusco/fromgoftolambda/examples/visitor/VisitorLambda.java b/src/main/java/org/mfusco/fromgoftolambda/examples/visitor/VisitorLambda.java
index 4c5a4b9..7c70d94 100644
--- a/src/main/java/org/mfusco/fromgoftolambda/examples/visitor/VisitorLambda.java
+++ b/src/main/java/org/mfusco/fromgoftolambda/examples/visitor/VisitorLambda.java
@@ -6,35 +6,12 @@
 import java.util.Map;
 import java.util.function.Function;
 
-public class VisitorLambda {
-
-    public static class LambdaVisitor<A> implements Function<Object, A> {
-        private Map<Class<?>, Function<Object, A>> fMap = new HashMap<>();
-
-        public <B> Acceptor<A, B> on(Class<B> clazz) {
-            return new Acceptor<>(this, clazz);
-        }
-
-        @Override
-        public A apply( Object o ) {
-            return fMap.get(o.getClass()).apply( o );
-        }
-
-        static class Acceptor<A, B> {
-            private final LambdaVisitor visitor;
-            private final Class<B> clazz;
+import static org.mfusco.fromgoftolambda.examples.visitor.Elements.circleElement;
+import static org.mfusco.fromgoftolambda.examples.visitor.Elements.rectangleElement;
+import static org.mfusco.fromgoftolambda.examples.visitor.Elements.squareElement;
 
-            public Acceptor( LambdaVisitor<A> visitor, Class<B> clazz ) {
-                this.visitor = visitor;
-                this.clazz = clazz;
-            }
+public class VisitorLambda {
 
-            public LambdaVisitor<A> then(Function<B, A> f) {
-                visitor.fMap.put( clazz, f );
-                return visitor;
-            }
-        }
-    }
 
     public static class Square {
         final double side;
@@ -62,18 +39,32 @@ public Rectangle( double weidht, double height ) {
         }
     }
 
-    static Function<Object, Double> areaVisitor = new LambdaVisitor<Double>()
-            .on(Square.class).then( s -> s.side * s.side )
-            .on(Circle.class).then( c -> Math.PI * c.radius * c.radius )
-            .on(Rectangle.class).then( r -> r.height * r.weidht );
+    @org.derive4j.Data
+    // see the generated "Elements" class for constructors (https://gist.github.com/jbgi/393f621decdeb1374b1f3356b2d140b6)
+    interface Element {
+        // we could have used the same visitor interface as in gof visitor... but let's go with an equivalent catamorphism definition:
+        <T> T match( Function<Square, T>    squareElement,
+                     Function<Circle, T>    circleElement,
+                     Function<Rectangle, T> rectangleElement );
+    }
+
+
+    // like with the visitor pattern, pattern matching synthax ensure that all 3 cases are handled:
+
+    static Function<Element, Double> areaVisitor = element -> element.match(
+              s -> s.side * s.side,
+              c -> Math.PI * c.radius * c.radius,
+              r -> r.height * r.weidht
+    );
 
-    static Function<Object, Double> perimeterVisitor = new LambdaVisitor<Double>()
-            .on(Square.class).then( s -> 4 * s.side )
-            .on(Circle.class).then( c -> 2 * Math.PI * c.radius )
-            .on(Rectangle.class).then( r -> 2 * r.height + 2 * r.weidht );
+    // or using the equivalent syntax generated by derive4j:
+    static Function<Element, Double> perimeterVisitor = Elements.cases()
+            .squareElement(    s -> 4 * s.side )
+            .circleElement(    c -> 2 * Math.PI * c.radius )
+            .rectangleElement( r -> 2 * r.height + 2 * r.weidht );
 
     public static void main( String[] args ) {
-        List<Object> figures = Arrays.asList( new Circle( 4 ), new Square( 5 ), new Rectangle( 6, 7 ) );
+        List<Element> figures = Arrays.asList( circleElement(new Circle( 4 )), squareElement(new Square( 5 )), rectangleElement(new Rectangle( 6, 7 )) );
 
         double totalArea = figures.stream().map( areaVisitor ).reduce( 0.0, (v1, v2) -> v1 + v2 );
         System.out.println("Total area = " + totalArea);