From 94d481c940fb36da896e2e80a62f39d849477f53 Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Thu, 2 Jul 2026 16:32:26 +0100
Subject: Add inductive data types example

---
 examples/03-inductive-data-types/hobgoblin.json5   | 15 +++++++++
 .../03-inductive-data-types/output/java/.gitignore |  2 ++
 .../03-inductive-data-types/output/java/pom.xml    | 39 ++++++++++++++++++++++
 .../src/main/java/org/zwobble/example/Main.java    | 17 ++++++++++
 .../03-inductive-data-types/src/arithmetic.hob     | 13 ++++++++
 5 files changed, 86 insertions(+)
 create mode 100644 examples/03-inductive-data-types/hobgoblin.json5
 create mode 100644 examples/03-inductive-data-types/output/java/.gitignore
 create mode 100644 examples/03-inductive-data-types/output/java/pom.xml
 create mode 100644 examples/03-inductive-data-types/output/java/src/main/java/org/zwobble/example/Main.java
 create mode 100644 examples/03-inductive-data-types/src/arithmetic.hob

(limited to 'examples/03-inductive-data-types')

diff --git a/examples/03-inductive-data-types/hobgoblin.json5 b/examples/03-inductive-data-types/hobgoblin.json5
new file mode 100644
index 0000000..28269ad
--- /dev/null
+++ b/examples/03-inductive-data-types/hobgoblin.json5
@@ -0,0 +1,15 @@
+{
+  outputs: {
+    langs: {
+      java: {
+        packageName: "org.zwobble.example.types",
+      },
+    },
+    generators: [
+      {
+        generator: "java-types",
+        path: "output/java/src/gen/java",
+      },
+    ],
+  },
+}
diff --git a/examples/03-inductive-data-types/output/java/.gitignore b/examples/03-inductive-data-types/output/java/.gitignore
new file mode 100644
index 0000000..ff511d4
--- /dev/null
+++ b/examples/03-inductive-data-types/output/java/.gitignore
@@ -0,0 +1,2 @@
+/src/gen/
+/target/
diff --git a/examples/03-inductive-data-types/output/java/pom.xml b/examples/03-inductive-data-types/output/java/pom.xml
new file mode 100644
index 0000000..7493667
--- /dev/null
+++ b/examples/03-inductive-data-types/output/java/pom.xml
@@ -0,0 +1,39 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+
+  <groupId>org.zwobble.hobgoblin.examples</groupId>
+  <artifactId>example</artifactId>
+  <version>1.0-SNAPSHOT</version>
+
+  <properties>
+    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    <maven.compiler.source>25</maven.compiler.source>
+    <maven.compiler.target>25</maven.compiler.target>
+  </properties>
+
+  <build>
+    <plugins>
+      <plugin>
+        <groupId>org.codehaus.mojo</groupId>
+        <artifactId>build-helper-maven-plugin</artifactId>
+        <version>3.6.1</version>
+        <executions>
+          <execution>
+            <id>add-source</id>
+            <phase>generate-sources</phase>
+            <goals>
+              <goal>add-source</goal>
+            </goals>
+            <configuration>
+              <sources>
+                <source>src/gen/java</source>
+              </sources>
+            </configuration>
+          </execution>
+        </executions>
+      </plugin>
+    </plugins>
+  </build>
+</project>
diff --git a/examples/03-inductive-data-types/output/java/src/main/java/org/zwobble/example/Main.java b/examples/03-inductive-data-types/output/java/src/main/java/org/zwobble/example/Main.java
new file mode 100644
index 0000000..901c9e8
--- /dev/null
+++ b/examples/03-inductive-data-types/output/java/src/main/java/org/zwobble/example/Main.java
@@ -0,0 +1,17 @@
+package org.zwobble.example;
+
+import org.zwobble.example.types.arithmetic.Add;
+import org.zwobble.example.types.arithmetic.Const;
+import org.zwobble.example.types.arithmetic.Expression;
+
+public class Main {
+    public static void main() {
+        Expression expression = new Add(
+            new Add(
+                new Const(42),
+                new Const(47)
+            ),
+            new Const(52)
+        );
+    }
+}
diff --git a/examples/03-inductive-data-types/src/arithmetic.hob b/examples/03-inductive-data-types/src/arithmetic.hob
new file mode 100644
index 0000000..b1ef6e5
--- /dev/null
+++ b/examples/03-inductive-data-types/src/arithmetic.hob
@@ -0,0 +1,13 @@
+sum Expression {
+    variant Add box;
+    variant Const;
+}
+
+struct Add {
+    field left: Expression;
+    field right: Expression;
+}
+
+struct Const {
+    field value: Int32;
+}
-- 
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