Type check generic struct definition

4 files changed, 99 insertions, 24 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 e61cb7a..97008b6 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/typechecker/TypeChecker.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/typechecker/TypeChecker.java
@@ -208,7 +208,17 @@ public class TypeChecker {
         TypeCheckerNamespaceContext context
     ) {
         var structType = new SimpleStructType(context.namespaceName(), untyped.name());
-        var metaType = new TypeLevelValueType(structType);
+
+        var structTypeOrConstructor = untyped.typeParams().isEmpty()
+            ? new TypeOrConstructor.Type<>(structType)
+            : new TypeOrConstructor.Constructor<>(new StructTypeConstructor(
+                untyped.typeParams().get().stream()
+                    .map(typeParam -> new TypeParam(structType, typeParam.name()))
+                    .toList(),
+                structType
+            ));
+        var metaType = new TypeLevelValueType(structTypeOrConstructor.value());
+
         context.declare(untyped.name(), metaType, untyped.source());
         return metaType;
     }
@@ -217,7 +227,17 @@ public class TypeChecker {
         UntypedStructDefinitionNode untyped,
         TypeCheckerNamespaceContext context
     ) {
-        var structType = (SimpleStructType) lookupMetaType(untyped.name(), untyped.source(), context);
+        var metaType = lookupTypeLevelValue(untyped.name(), untyped.source(), context);
+        var typeOrConstructor = switch (metaType) {
+            case SimpleStructType type ->
+                new TypeOrConstructor.Type<>(type);
+
+            case StructTypeConstructor typeConstructor ->
+                new TypeOrConstructor.Constructor<>(typeConstructor);
+
+            default ->
+                throw new UnsupportedOperationException("TODO");
+        };
 
         var typeCheckedFieldDefinitions = untyped.fields().isPresent()
             ? Optional.of(typeCheckFieldDefinitions(untyped.fields().get(), context))
@@ -225,21 +245,24 @@ public class TypeChecker {
         var typedFields = typeCheckedFieldDefinitions.map(TypeCheckFieldDefinitionsResult::fields);
         var typedFieldNodes = typeCheckedFieldDefinitions.map(TypeCheckFieldDefinitionsResult::typedFieldNodes);
 
-        context.defineStructType(structType, typedFields);
+        context.defineStructType(typeOrConstructor.unboundType(), typedFields);
 
-        for (var sumType : context.variantOf(structType)) {
-            var sumTypeFields = context.fieldsOf(sumType);
-            typeCheckVariantType(
-                sumType,
-                sumTypeFields,
-                structType,
-                typedFields,
-                context.toTypesInfo()
-            );
+        // TODO: handle sums with generic structs
+        if (typeOrConstructor instanceof TypeOrConstructor.Type<SimpleStructType> type) {
+            for (var sumType : context.variantOf(type.value())) {
+                var sumTypeFields = context.fieldsOf(sumType);
+                typeCheckVariantType(
+                    sumType,
+                    sumTypeFields,
+                    type.value(),
+                    typedFields,
+                    context.toTypesInfo()
+                );
+            }
         }
 
         return new TypedStructDefinitionNode(
-            TypeOrConstructor.type(structType),
+            typeOrConstructor,
             typedFieldNodes,
             untyped.docComment(),
             untyped.source()
diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/types/TypeOrConstructor.java b/src/main/java/org/zwobble/hobgoblin/compiler/types/TypeOrConstructor.java
index 3cffbc6..7904d29 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/types/TypeOrConstructor.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/types/TypeOrConstructor.java
@@ -14,6 +14,11 @@ public sealed interface TypeOrConstructor<T extends ConstructibleType> {
         public String name() {
             return this.value.name();
         }
+
+        @Override
+        public T unboundType() {
+            return value;
+        }
     }
 
     record Constructor<T extends ConstructibleType>(TypeConstructor<T> value) implements TypeOrConstructor<T> {
@@ -21,8 +26,14 @@ public sealed interface TypeOrConstructor<T extends ConstructibleType> {
         public String name() {
             return this.value.name();
         }
+
+        @Override
+        public T unboundType() {
+            return this.value.genericType();
+        }
     }
 
     String name();
     TypeLevelValue value();
+    T unboundType();
 }
diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/types/Types.java b/src/main/java/org/zwobble/hobgoblin/compiler/types/Types.java
index 094a419..cfbb5ba 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/types/Types.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/types/Types.java
@@ -18,4 +18,12 @@ public class Types {
                 new StructTypeConstructor(params, simpleStructType);
         };
     }
+
+    public static Type metaType(Type type) {
+        return new TypeLevelValueType(type);
+    }
+
+    public static Type metaType(TypeConstructor<?> constructor) {
+        return new TypeLevelValueType(constructor);
+    }
 }
diff --git a/src/test/java/org/zwobble/hobgoblin/compiler/typechecker/TypeCheckerStructDefinitionTests.java b/src/test/java/org/zwobble/hobgoblin/compiler/typechecker/TypeCheckerStructDefinitionTests.java
index 9bdf9f8..91839f6 100644
--- a/src/test/java/org/zwobble/hobgoblin/compiler/typechecker/TypeCheckerStructDefinitionTests.java
+++ b/src/test/java/org/zwobble/hobgoblin/compiler/typechecker/TypeCheckerStructDefinitionTests.java
@@ -5,13 +5,8 @@ import org.zwobble.hobgoblin.compiler.ast.typed.TypedNamespaceNode;
 import org.zwobble.hobgoblin.compiler.ast.typed.TypedStructDefinitionNode;
 import org.zwobble.hobgoblin.compiler.ast.typed.TypedStructFieldDefinitionNode;
 import org.zwobble.hobgoblin.compiler.ast.typed.TypedTypeLevelExpressionNode;
-import org.zwobble.hobgoblin.compiler.ast.untyped.UntypedArb;
-import org.zwobble.hobgoblin.compiler.ast.untyped.UntypedNamespaceNode;
-import org.zwobble.hobgoblin.compiler.ast.untyped.UntypedStructDefinitionNode;
-import org.zwobble.hobgoblin.compiler.ast.untyped.UntypedStructFieldDefinitionNode;
-import org.zwobble.hobgoblin.compiler.types.NamespaceName;
-import org.zwobble.hobgoblin.compiler.types.SimpleNativeType;
-import org.zwobble.hobgoblin.compiler.types.SimpleStructType;
+import org.zwobble.hobgoblin.compiler.ast.untyped.*;
+import org.zwobble.hobgoblin.compiler.types.*;
 
 import java.util.List;
 import java.util.Optional;
@@ -23,7 +18,7 @@ import static org.zwobble.precisely.Matchers.*;
 
 public class TypeCheckerStructDefinitionTests {
     @Test
-    public void structHasNamespaceFromContext() {
+    public void whenStructDefinitionHasNoTypeParamsThenNameIsBoundToType() {
         var untyped = UntypedStructDefinitionNode.arbitrary()
             .withName("X")
             .build();
@@ -31,14 +26,52 @@ public class TypeCheckerStructDefinitionTests {
 
         var typed = typeCheckNamespaceStatement(untyped, context);
 
+        var expectedType = new SimpleStructType(NamespaceName.of("a", "b"), "X");
         assertThat(typed, instanceOf(
             TypedStructDefinitionNode.class,
             has(
-                "type",
-                TypedStructDefinitionNode::typeOrThrow,
-                equalTo(new SimpleStructType(NamespaceName.of("a", "b"), "X"))
+                "typeOrConstructor",
+                TypedStructDefinitionNode::typeOrConstructor,
+                equalTo(TypeOrConstructor.type(expectedType))
             )
         ));
+        assertThat(context.lookupType("X"), isOptionalOf(
+            equalTo(Types.metaType(expectedType))
+        ));
+    }
+
+    @Test
+    public void whenStructDefinitionHasTypeParamsThenNameIsBoundToTypeConstructor() {
+        var untyped = UntypedStructDefinitionNode.arbitrary()
+            .withName("X")
+            .withTypeParams(Optional.of(List.of(
+                UntypedTypeParamNode.arbitrary().withName("A").build(),
+                UntypedTypeParamNode.arbitrary().withName("B").build()
+            )))
+            .build();
+        var context = TypeCheckerContextArb.namespaceContext(NamespaceName.of("a", "b"));
+
+        var typed = typeCheckNamespaceStatement(untyped, context);
+
+        var expectedInnerType = new SimpleStructType(NamespaceName.of("a", "b"), "X");
+        var expectedTypeConstructor = Types.constructor(
+            List.of(
+                new TypeParam(expectedInnerType, "A"),
+                new TypeParam(expectedInnerType, "B")
+            ),
+            expectedInnerType
+        );
+        assertThat(typed, instanceOf(
+            TypedStructDefinitionNode.class,
+            has(
+                "typeOrConstructor",
+                TypedStructDefinitionNode::typeOrConstructor,
+                equalTo(TypeOrConstructor.constructor(expectedTypeConstructor))
+            )
+        ));
+        assertThat(context.lookupType("X"), isOptionalOf(
+            equalTo(Types.metaType(expectedTypeConstructor))
+        ));
     }
 
     @Test