diff --git a/slides.md b/slides.md
index 655381b..9a053bb 100644
--- a/slides.md
+++ b/slides.md
@@ -276,7 +276,7 @@
 
 ---
 
-# JEPs
+# Links
 
 - [Switch expressions](https://openjdk.org/jeps/361) 14
 - [Records](https://openjdk.org/jeps/395) 16
@@ -284,4 +284,5 @@
 - [Pattern matching for switch](https://openjdk.org/jeps/441) 21
 - [Record patterns](https://openjdk.org/jeps/440) 21
 - [Unnamed variables and patterns](https://openjdk.org/jeps/456) 22
-- [Primitive types in patterns](https://openjdk.org/jeps/455) 23 (1st preview)
\ No newline at end of file
+- [Primitive types in patterns](https://openjdk.org/jeps/455) 23 (1st preview)
+- [Data Oriented Programmig](https://www.infoq.com/articles/data-oriented-programming-java/) Brian Goetz
\ No newline at end of file
diff --git a/snippets/Expr.java b/snippets/Expr.java
new file mode 100644
index 0000000..8ad42bb
--- /dev/null
+++ b/snippets/Expr.java
@@ -0,0 +1,39 @@
+package snippets;
+
+public sealed interface Expr {
+
+    record Lit(int value) implements Expr {}
+    record Sum(Expr left, Expr right) implements Expr {}
+    record Diff(Expr left, Expr right) implements Expr {}
+    record Times(Expr left, Expr right) implements Expr {}
+
+    default int evaluate() {
+        return switch (this) {
+            case Lit(var value) -> value;
+            case Sum(var left, var right) -> left.evaluate() + right.evaluate();
+            case Diff(var left, var right) -> left.evaluate() - right.evaluate();
+            case Times(var left, var right) -> left.evaluate() * right.evaluate();
+        };
+    }
+
+    static Expr lit(int value) {
+        return new Lit(value);
+    }
+
+    static Expr sum(Expr left, Expr right) {
+        return new Sum(left, right);
+    }
+
+    static Expr diff(Expr left, Expr right) {
+        return new Diff(left, right);
+    }
+
+    static Expr times(Expr left, Expr right) {
+        return new Times(left, right);
+    }
+
+    static void run() {
+        sum(lit(1), lit(2)).evaluate(); // 3
+        sum(diff(lit(10), lit(8)), lit(2)).evaluate(); // 4
+    }
+}