From 4ba00f412eff5f0c63371f98abcb41a82fd0819b Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Sat, 13 Jun 2026 21:16:42 +0100
Subject: Generate fields on Java interface for sum fields

---
 .../generators/javatypes/JavaTypesGenerator.java       | 18 +++++++++++++++---
 .../output/lang/java/ast/JavaTypeDeclaration.java      |  6 ++++--
 2 files changed, 19 insertions(+), 5 deletions(-)

(limited to 'src/main/java/org')

diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/output/generators/javatypes/JavaTypesGenerator.java b/src/main/java/org/zwobble/hobgoblin/compiler/output/generators/javatypes/JavaTypesGenerator.java
index 827cab9..3187b27 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/output/generators/javatypes/JavaTypesGenerator.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/output/generators/javatypes/JavaTypesGenerator.java
@@ -223,15 +223,27 @@ public class JavaTypesGenerator implements Generator {
         TypedSumDefinitionNode sumDefinition,
         Context context
     ) {
+        var body = new ArrayList<JavaClassBodyDeclaration>();
+        body.add(generateSumDefinitionBuilder(sumDefinition, context));
+
+        for (var field : sumDefinition.fields()) {
+            body.add(new JavaMethodDeclaration(
+                field.name(),
+                JavaVisibility.PUBLIC,
+                JavaMethodKind.INSTANCE,
+                generateTypeRef(field.type().value(), context),
+                List.of(),
+                Optional.empty()
+            ));
+        }
+
         return new JavaInterfaceDeclaration(
             sumDefinition.name(),
             JavaInterfaceOpenness.SEALED,
             sumDefinition.variants().stream()
                 .map(variant -> generateTypeRef(variant.type(), context))
                 .toList(),
-            List.of(
-                generateSumDefinitionBuilder(sumDefinition, context)
-            ),
+            body,
             JavaCustomArea.forType(generateTypeRef(sumDefinition.type(), context), "body"),
             sumDefinition.docComment()
         );
diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/ast/JavaTypeDeclaration.java b/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/ast/JavaTypeDeclaration.java
index 1824efc..b4c5d49 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/ast/JavaTypeDeclaration.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/ast/JavaTypeDeclaration.java
@@ -10,8 +10,10 @@ public sealed interface JavaTypeDeclaration permits org.zwobble.hobgoblin.compil
         // Custom area end: org.zwobble.hobgoblin.compiler.output.lang.java.ast.JavaTypeDeclaration.Builder body
     }
 
+    public String name();
+
+    public org.zwobble.hobgoblin.compiler.output.lang.java.ast.JavaCustomArea customArea();
+
     // Custom area start: org.zwobble.hobgoblin.compiler.output.lang.java.ast.JavaTypeDeclaration body
-    String name();
-    JavaCustomArea customArea();
     // Custom area end: org.zwobble.hobgoblin.compiler.output.lang.java.ast.JavaTypeDeclaration body
 }
-- 
cgit v1.2.3