From 4b64acb0313807b766a60a402843218957479ed5 Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Tue, 28 Apr 2026 23:36:24 +0100
Subject: Add SumType

---
 .../generators/javatypes/JavaTypesGenerator.java   | 29 ++++++++++++++--------
 .../zwobble/hobgoblin/compiler/types/SumType.java  |  8 ++++++
 .../org/zwobble/hobgoblin/compiler/types/Type.java |  2 +-
 3 files changed, 28 insertions(+), 11 deletions(-)
 create mode 100644 src/main/java/org/zwobble/hobgoblin/compiler/types/SumType.java

(limited to 'src/main')

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 c638763..71fdba9 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
@@ -11,9 +11,7 @@ import org.zwobble.hobgoblin.compiler.output.java.ast.JavaRecordComponent;
 import org.zwobble.hobgoblin.compiler.output.java.ast.JavaRecordDeclaration;
 import org.zwobble.hobgoblin.compiler.output.java.ast.JavaCompilationUnit;
 import org.zwobble.hobgoblin.compiler.output.java.ast.JavaTypeRef;
-import org.zwobble.hobgoblin.compiler.types.NamespaceName;
-import org.zwobble.hobgoblin.compiler.types.StructType;
-import org.zwobble.hobgoblin.compiler.types.Type;
+import org.zwobble.hobgoblin.compiler.types.*;
 
 import java.io.File;
 import java.io.IOException;
@@ -79,12 +77,23 @@ public class JavaTypesGenerator implements Generator {
     private JavaTypeRef generateTypeRef(TypedTypeLevelExpressionNode<Type> typeNode) {
         var type = typeNode.value();
 
-        if (type instanceof StructType structType) {
-            return new JavaTypeRef(namespaceToJavaPackageParts(structType.namespaceName()), structType.name());
-        } else if (type.equals(BuiltinTypes.INT_32)) {
-            return new JavaTypeRef(List.of(), "int");
-        } else {
-            throw new UnsupportedOperationException("TODO");
-        }
+        return switch (type) {
+            case StructType structType ->
+                new JavaTypeRef(namespaceToJavaPackageParts(structType.namespaceName()), structType.name());
+
+            case SumType sumType ->
+                new JavaTypeRef(namespaceToJavaPackageParts(sumType.namespaceName()), sumType.name());
+
+            case ScalarType scalarType -> {
+                if (type.equals(BuiltinTypes.INT_32)) {
+                    yield new JavaTypeRef(List.of(), "int");
+                } else {
+                    throw new UnsupportedOperationException("TODO");
+                }
+            }
+
+            case TypeLevelValueType typeLevelValueType ->
+                throw new UnsupportedOperationException("TODO");
+        };
     }
 }
diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/types/SumType.java b/src/main/java/org/zwobble/hobgoblin/compiler/types/SumType.java
new file mode 100644
index 0000000..2517b6a
--- /dev/null
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/types/SumType.java
@@ -0,0 +1,8 @@
+package org.zwobble.hobgoblin.compiler.types;
+
+public record SumType(NamespaceName namespaceName, String name) implements Type {
+    @Override
+    public String describe() {
+        return namespaceName.toString() + "." + name;
+    }
+}
diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/types/Type.java b/src/main/java/org/zwobble/hobgoblin/compiler/types/Type.java
index f7b6833..bb3f375 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/types/Type.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/types/Type.java
@@ -1,4 +1,4 @@
 package org.zwobble.hobgoblin.compiler.types;
 
-public sealed interface Type extends TypeLevelValue permits ScalarType, StructType, TypeLevelValueType {
+public sealed interface Type extends TypeLevelValue permits ScalarType, StructType, SumType, TypeLevelValueType {
 }
-- 
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