3 files changed, 42 insertions, 3 deletions
diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/ast/untyped/UntypedNamespaceStatementNode.java b/src/main/java/org/zwobble/hobgoblin/compiler/ast/untyped/UntypedNamespaceStatementNode.java
index ef1ca5e..0627a6b 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/ast/untyped/UntypedNamespaceStatementNode.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/ast/untyped/UntypedNamespaceStatementNode.java
@@ -1,6 +1,13 @@
 package org.zwobble.hobgoblin.compiler.ast.untyped;
 
 public sealed interface UntypedNamespaceStatementNode permits org.zwobble.hobgoblin.compiler.ast.untyped.UntypedNativeTypeDefinitionNode, org.zwobble.hobgoblin.compiler.ast.untyped.UntypedStructDefinitionNode, org.zwobble.hobgoblin.compiler.ast.untyped.UntypedSumDefinitionNode {
+    public interface Builder {
+        public org.zwobble.hobgoblin.compiler.ast.untyped.UntypedNamespaceStatementNode build();
+
+        // Custom area start: org.zwobble.hobgoblin.compiler.ast.untyped.UntypedNamespaceStatementNode.Builder body
+        // Custom area end: org.zwobble.hobgoblin.compiler.ast.untyped.UntypedNamespaceStatementNode.Builder body
+    }
+
     // Custom area start: org.zwobble.hobgoblin.compiler.ast.untyped.UntypedNamespaceStatementNode body
     // Custom area end: org.zwobble.hobgoblin.compiler.ast.untyped.UntypedNamespaceStatementNode body
 }
diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/ast/untyped/UntypedTypeLevelExpressionNode.java b/src/main/java/org/zwobble/hobgoblin/compiler/ast/untyped/UntypedTypeLevelExpressionNode.java
index 3884c1f..c2e484c 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/ast/untyped/UntypedTypeLevelExpressionNode.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/ast/untyped/UntypedTypeLevelExpressionNode.java
@@ -1,6 +1,13 @@
 package org.zwobble.hobgoblin.compiler.ast.untyped;
 
 public sealed interface UntypedTypeLevelExpressionNode permits org.zwobble.hobgoblin.compiler.ast.untyped.UntypedTypeLevelReferenceNode, org.zwobble.hobgoblin.compiler.ast.untyped.UntypedConstructedTypeNode {
+    public interface Builder {
+        public org.zwobble.hobgoblin.compiler.ast.untyped.UntypedTypeLevelExpressionNode build();
+
+        // Custom area start: org.zwobble.hobgoblin.compiler.ast.untyped.UntypedTypeLevelExpressionNode.Builder body
+        // Custom area end: org.zwobble.hobgoblin.compiler.ast.untyped.UntypedTypeLevelExpressionNode.Builder body
+    }
+
     // Custom area start: org.zwobble.hobgoblin.compiler.ast.untyped.UntypedTypeLevelExpressionNode body
     // Custom area end: org.zwobble.hobgoblin.compiler.ast.untyped.UntypedTypeLevelExpressionNode body
 }
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 867ba23..5af408c 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
@@ -143,7 +143,24 @@ public class JavaTypesGenerator implements Generator {
                             sumDefinition.variants().stream()
                                 .map(variant -> generateTypeRef(variant.type(), context))
                                 .toList(),
-                            List.of(),
+                            List.of(
+                                new JavaInterfaceDeclaration(
+                                    BUILDER_TYPE_NAME,
+                                    JavaInterfaceDeclaration.Openness.OPEN,
+                                    List.of(),
+                                    List.of(
+                                        new JavaMethodDeclaration(
+                                            "build",
+                                            JavaMethodKind.INSTANCE,
+                                            generateTypeRef(sumDefinition.type(), context),
+                                            List.of(),
+                                            Optional.empty()
+                                        )
+                                    ),
+                                    JavaCustomArea.type(generateBuilderTypeRef(sumDefinition.type()), "body"),
+                                    DocComment.EMPTY
+                                )
+                            ),
                             JavaCustomArea.type(generateTypeRef(sumDefinition.type(), context), "body"),
                             sumDefinition.docComment()
                         )
@@ -308,8 +325,16 @@ public class JavaTypesGenerator implements Generator {
     }
 
     private JavaTypeRef generateBuilderTypeRef(StructType type) {
-        var javaPackage = namespaceToJavaPackageParts(type.namespaceName());
-        return JavaTypeRef.inner(javaPackage, type.name(), BUILDER_TYPE_NAME);
+        return generateBuilderTypeRef(type.namespaceName(), type.name());
+    }
+
+    private JavaTypeRef generateBuilderTypeRef(SumType type) {
+        return generateBuilderTypeRef(type.namespaceName(), type.name());
+    }
+
+    private JavaTypeRef generateBuilderTypeRef(NamespaceName namespaceName, String name) {
+        var javaPackage = namespaceToJavaPackageParts(namespaceName);
+        return JavaTypeRef.inner(javaPackage, name, BUILDER_TYPE_NAME);
     }
 
     private JavaExpression arbitraryValue(