From 8455bb19b7d4235e667cab9112aa276557969dcc Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Wed, 5 Aug 2026 18:44:26 +0100
Subject: Type check generic native types

---
 .../ast/typed/TypedNativeTypeDefinitionNode.java   |  5 +++--
 .../compiler/typechecker/TypeChecker.java          | 26 +++++++++++++++++++---
 .../hobgoblin/compiler/types/TypeConstructor.java  |  4 ++++
 .../compiler/types/TypeOrConstructor.java          | 20 +++++++++++++++++
 4 files changed, 50 insertions(+), 5 deletions(-)
 create mode 100644 src/main/java/org/zwobble/hobgoblin/compiler/types/TypeOrConstructor.java

(limited to 'src/main')

diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/ast/typed/TypedNativeTypeDefinitionNode.java b/src/main/java/org/zwobble/hobgoblin/compiler/ast/typed/TypedNativeTypeDefinitionNode.java
index e81705b..487a80b 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/ast/typed/TypedNativeTypeDefinitionNode.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/ast/typed/TypedNativeTypeDefinitionNode.java
@@ -3,13 +3,14 @@ package org.zwobble.hobgoblin.compiler.ast.typed;
 import org.zwobble.hobgoblin.compiler.ast.DocComment;
 import org.zwobble.hobgoblin.compiler.sources.Source;
 import org.zwobble.hobgoblin.compiler.types.SimpleNativeType;
+import org.zwobble.hobgoblin.compiler.types.TypeOrConstructor;
 
 public record TypedNativeTypeDefinitionNode(
-    SimpleNativeType type,
+    TypeOrConstructor<SimpleNativeType> typeOrConstructor,
     DocComment docComment,
     Source source
 ) implements TypedNamespaceStatementNode {
     public String name() {
-        return this.type.name();
+        return this.typeOrConstructor.name();
     }
 }
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 eb47870..e403f5b 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/typechecker/TypeChecker.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/typechecker/TypeChecker.java
@@ -165,7 +165,17 @@ public class TypeChecker {
         TypeCheckerNamespaceContext context
     ) {
         var nativeType = new SimpleNativeType(context.namespaceName(), untyped.name());
-        var metaType = new TypeLevelValueType(nativeType);
+
+        var nativeTypeOrConstructor = untyped.typeParams().isEmpty()
+            ? new TypeOrConstructor.Type<>(nativeType)
+            : new TypeOrConstructor.Constructor<>(new NativeTypeConstructor(
+                untyped.typeParams().stream()
+                    .map(typeParam -> new TypeParam(typeParam.name()))
+                    .toList(),
+                nativeType
+            ));
+
+        var metaType = new TypeLevelValueType(nativeTypeOrConstructor.value());
         context.declare(untyped.name(), metaType, untyped.source());
         return metaType;
     }
@@ -174,10 +184,20 @@ public class TypeChecker {
         UntypedNativeTypeDefinitionNode untyped,
         TypeCheckerNamespaceContext context
     ) {
-        var nativeType = (SimpleNativeType) lookupMetaType(untyped.name(), untyped.source(), context);
+        var nativeMetaType = lookupTypeLevelValue(untyped.name(), untyped.source(), context);
+        var nativeTypeOrConstructor = switch (nativeMetaType) {
+            case SimpleNativeType type ->
+                new TypeOrConstructor.Type<>(type);
+
+            case NativeTypeConstructor typeConstructor ->
+                new TypeOrConstructor.Constructor<>(typeConstructor);
+
+            default ->
+                throw new UnsupportedOperationException("TODO");
+        };
 
         return new TypedNativeTypeDefinitionNode(
-            nativeType,
+            nativeTypeOrConstructor,
             untyped.docComment(),
             untyped.source()
         );
diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/types/TypeConstructor.java b/src/main/java/org/zwobble/hobgoblin/compiler/types/TypeConstructor.java
index e2726fb..2c779d2 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/types/TypeConstructor.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/types/TypeConstructor.java
@@ -9,4 +9,8 @@ public sealed interface TypeConstructor<T extends ConstructibleType> extends Typ
     default String describe() {
         return genericType().describe();
     }
+
+    default String name() {
+        return genericType().name();
+    }
 }
diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/types/TypeOrConstructor.java b/src/main/java/org/zwobble/hobgoblin/compiler/types/TypeOrConstructor.java
new file mode 100644
index 0000000..8844669
--- /dev/null
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/types/TypeOrConstructor.java
@@ -0,0 +1,20 @@
+package org.zwobble.hobgoblin.compiler.types;
+
+public sealed interface TypeOrConstructor<T extends ConstructibleType> {
+    record Type<T extends ConstructibleType>(T value) implements TypeOrConstructor<T> {
+        @Override
+        public String name() {
+            return this.value.name();
+        }
+    }
+
+    record Constructor<T extends ConstructibleType>(TypeConstructor<T> value) implements TypeOrConstructor<T> {
+        @Override
+        public String name() {
+            return this.value.name();
+        }
+    }
+
+    String name();
+    TypeLevelValue value();
+}
-- 
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