From 066af00eebe662e5a589a4e274e1613201b36982 Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Thu, 2 Jul 2026 09:57:35 +0100
Subject: Support translating sums into Rust types

---
 .../generators/rusttypes/RustTypesGenerator.java   | 31 +++++++++++++++++++++-
 1 file changed, 30 insertions(+), 1 deletion(-)

(limited to 'src/main')

diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/output/generators/rusttypes/RustTypesGenerator.java b/src/main/java/org/zwobble/hobgoblin/compiler/output/generators/rusttypes/RustTypesGenerator.java
index 99151c4..e681a3e 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/output/generators/rusttypes/RustTypesGenerator.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/output/generators/rusttypes/RustTypesGenerator.java
@@ -92,7 +92,7 @@ public class RustTypesGenerator implements Generator {
             }
 
             case TypedSumDefinitionNode sumDefinition -> {
-                yield List.of();
+                yield generateSumDefinition(sumDefinition, context);
             }
         };
     }
@@ -115,6 +115,26 @@ public class RustTypesGenerator implements Generator {
         return List.of(rustStruct);
     }
 
+    private List<RustItem> generateSumDefinition(
+        TypedSumDefinitionNode sumDefinition,
+        Context context
+    ) {
+        var rustEnumName = generateTypeName(sumDefinition.name());
+
+        var rustVariants = sumDefinition.variants().stream()
+            .map(variant -> new RustEnumVariant(
+                generateVariantName(variant.type().value()),
+                new RustEnumVariantTuple(List.of(
+                    new RustTupleField(generateRustTypeExpression(variant.type(), context))
+                ))
+            ))
+            .toList();
+
+        var rustEnum = new RustEnum(rustEnumName, rustVariants, sumDefinition.docComment());
+
+        return List.of(rustEnum);
+    }
+
     private RustType generateRustTypeExpression(
         TypedTypeLevelExpressionNode<Type> type,
         Context context
@@ -196,6 +216,15 @@ public class RustTypesGenerator implements Generator {
         return new RustIdentifier(Casing.lowerCamelCaseToSnakeCase(part));
     }
 
+    private RustIdentifier generateVariantName(Type type) {
+        if (type instanceof StructType structType) {
+            return generateTypeName(structType.name());
+        } else {
+            throw new UnsupportedOperationException("TODO");
+        }
+
+    }
+
     private static class Context {
         private final NamespaceName currentNamespaceName;
 
-- 
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