1 files changed, 20 insertions, 2 deletions
diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/typechecker/TypeChecker.java b/src/main/java/org/zwobble/hobgoblin/compiler/typechecker/TypeChecker.java
index 84cb6aa..c713c70 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/typechecker/TypeChecker.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/typechecker/TypeChecker.java
@@ -97,14 +97,32 @@ public class TypeChecker {
         UntypedSumDefinitionNode untyped,
         TypeCheckerNamespaceContext context
     ) {
-        throw new UnsupportedOperationException("TODO");
+        var sumType = new SumType(context.namespaceName(), untyped.name());
+        // TODO: tidy up declare vs define
+        context.declare(untyped.name());
+        context.define(untyped.name(), new TypeLevelValueType(sumType));
     }
 
     private static TypedNamespaceStatementNode defineSumDefinition(
         UntypedSumDefinitionNode untyped,
         TypeCheckerNamespaceContext context
     ) {
-        throw new UnsupportedOperationException("TODO");
+        var sumType = (SumType) lookupMetaType(untyped.name(), untyped.source(), context);
+
+        var typedVariants = new ArrayList<TypedSumVariantDefinitionNode>();
+        for (var untypedVariant : untyped.variants()) {
+            var typedVariant = new TypedSumVariantDefinitionNode(
+                typeCheckMetaType(untypedVariant.type(), context),
+                untyped.source()
+            );
+            typedVariants.add(typedVariant);
+        }
+
+        return new TypedSumDefinitionNode(
+            sumType,
+            typedVariants,
+            untyped.source()
+        );
     }
 
     private static TypedTypeLevelExpressionNode<Type> typeCheckMetaType(