diff --git a/Meta/Lagom/Tools/CodeGenerators/LibWeb/WrapperGenerator/IDLGenerators.cpp b/Meta/Lagom/Tools/CodeGenerators/LibWeb/WrapperGenerator/IDLGenerators.cpp
index 5e5def38326..a760c7b56ba 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibWeb/WrapperGenerator/IDLGenerators.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/LibWeb/WrapperGenerator/IDLGenerators.cpp
@@ -16,47 +16,48 @@ Vector<StringView> s_header_search_paths;
 
 namespace IDL {
 
+// FIXME: Generate this automatically somehow.
 static bool is_wrappable_type(Type const& type)
 {
-    if (type.name == "EventTarget")
+    if (type.name() == "EventTarget")
         return true;
-    if (type.name == "Node")
+    if (type.name() == "Node")
         return true;
-    if (type.name == "Document")
+    if (type.name() == "Document")
         return true;
-    if (type.name == "Text")
+    if (type.name() == "Text")
         return true;
-    if (type.name == "DocumentType")
+    if (type.name() == "DocumentType")
         return true;
-    if (type.name.ends_with("Element"sv))
+    if (type.name().ends_with("Element"sv))
         return true;
-    if (type.name.ends_with("Event"sv))
+    if (type.name().ends_with("Event"sv))
         return true;
-    if (type.name == "ImageData")
+    if (type.name() == "ImageData")
         return true;
-    if (type.name == "Window")
+    if (type.name() == "Window")
         return true;
-    if (type.name == "Range")
+    if (type.name() == "Range")
         return true;
-    if (type.name == "Selection")
+    if (type.name() == "Selection")
         return true;
-    if (type.name == "Attribute")
+    if (type.name() == "Attribute")
         return true;
-    if (type.name == "NamedNodeMap")
+    if (type.name() == "NamedNodeMap")
         return true;
-    if (type.name == "TextMetrics")
+    if (type.name() == "TextMetrics")
         return true;
-    if (type.name == "AbortSignal")
+    if (type.name() == "AbortSignal")
         return true;
-    if (type.name == "CanvasRenderingContext2D")
+    if (type.name() == "CanvasRenderingContext2D")
         return true;
-    if (type.name == "WebGLRenderingContext")
+    if (type.name() == "WebGLRenderingContext")
         return true;
-    if (type.name == "URLSearchParams")
+    if (type.name() == "URLSearchParams")
         return true;
-    if (type.name == "Blob")
+    if (type.name() == "Blob")
         return true;
-    if (type.name == "Path2D")
+    if (type.name() == "Path2D")
         return true;
     return false;
 }
@@ -75,99 +76,99 @@ static StringView sequence_storage_type_to_cpp_storage_type_name(SequenceStorage
 
 static bool impl_is_wrapper(Type const& type)
 {
-    if (type.name == "StyleSheet"sv)
+    if (type.name() == "StyleSheet"sv)
         return true;
 
-    if (type.name == "CSSStyleSheet"sv)
+    if (type.name() == "CSSStyleSheet"sv)
         return true;
 
-    if (type.name == "StyleSheetList"sv)
+    if (type.name() == "StyleSheetList"sv)
         return true;
 
-    if (type.name == "CSSRuleList"sv)
+    if (type.name() == "CSSRuleList"sv)
         return true;
 
-    if (type.name == "CSSRule"sv)
+    if (type.name() == "CSSRule"sv)
         return true;
 
-    if (type.name == "CSSStyleRule"sv)
+    if (type.name() == "CSSStyleRule"sv)
         return true;
 
-    if (type.name == "CSSFontFaceRule"sv)
+    if (type.name() == "CSSFontFaceRule"sv)
         return true;
 
-    if (type.name == "CSSConditionRule"sv)
+    if (type.name() == "CSSConditionRule"sv)
         return true;
 
-    if (type.name == "CSSGroupingRule"sv)
+    if (type.name() == "CSSGroupingRule"sv)
         return true;
 
-    if (type.name == "CSSMediaRule"sv)
+    if (type.name() == "CSSMediaRule"sv)
         return true;
 
-    if (type.name == "CSSImportRule"sv)
+    if (type.name() == "CSSImportRule"sv)
         return true;
 
-    if (type.name == "EventTarget"sv)
+    if (type.name() == "EventTarget"sv)
         return true;
 
-    if (type.name == "Node"sv)
+    if (type.name() == "Node"sv)
         return true;
-    if (type.name == "ShadowRoot"sv)
+    if (type.name() == "ShadowRoot"sv)
         return true;
-    if (type.name == "DocumentTemporary"sv)
+    if (type.name() == "DocumentTemporary"sv)
         return true;
-    if (type.name == "Text"sv)
+    if (type.name() == "Text"sv)
         return true;
-    if (type.name == "Document"sv)
+    if (type.name() == "Document"sv)
         return true;
-    if (type.name == "DocumentType"sv)
+    if (type.name() == "DocumentType"sv)
         return true;
-    if (type.name.ends_with("Element"sv))
+    if (type.name().ends_with("Element"sv))
         return true;
-    if (type.name == "XMLHttpRequest"sv)
+    if (type.name() == "XMLHttpRequest"sv)
         return true;
-    if (type.name == "XMLHttpRequestEventTarget"sv)
+    if (type.name() == "XMLHttpRequestEventTarget"sv)
         return true;
-    if (type.name == "AbortSignal"sv)
+    if (type.name() == "AbortSignal"sv)
         return true;
-    if (type.name == "WebSocket"sv)
+    if (type.name() == "WebSocket"sv)
         return true;
-    if (type.name == "Worker"sv)
+    if (type.name() == "Worker"sv)
         return true;
-    if (type.name == "NodeIterator"sv)
+    if (type.name() == "NodeIterator"sv)
         return true;
-    if (type.name == "TreeWalker"sv)
+    if (type.name() == "TreeWalker"sv)
         return true;
-    if (type.name == "MediaQueryList"sv)
+    if (type.name() == "MediaQueryList"sv)
         return true;
-    if (type.name == "MessagePort"sv)
+    if (type.name() == "MessagePort"sv)
         return true;
-    if (type.name == "NodeFilter"sv)
+    if (type.name() == "NodeFilter"sv)
         return true;
-    if (type.name == "DOMTokenList"sv)
+    if (type.name() == "DOMTokenList"sv)
         return true;
-    if (type.name == "DOMStringMap"sv)
+    if (type.name() == "DOMStringMap"sv)
         return true;
-    if (type.name == "MutationRecord"sv)
+    if (type.name() == "MutationRecord"sv)
         return true;
-    if (type.name == "CanvasRenderingContext2D"sv)
+    if (type.name() == "CanvasRenderingContext2D"sv)
         return true;
-    if (type.name == "WebGLRenderingContext"sv)
+    if (type.name() == "WebGLRenderingContext"sv)
         return true;
-    if (type.name == "Path2D"sv)
+    if (type.name() == "Path2D"sv)
         return true;
-    if (type.name == "Storage"sv)
+    if (type.name() == "Storage"sv)
         return true;
-    if (type.name == "File"sv)
+    if (type.name() == "File"sv)
         return true;
-    if (type.name == "Blob"sv)
+    if (type.name() == "Blob"sv)
         return true;
-    if (type.name == "URL"sv)
+    if (type.name() == "URL"sv)
         return true;
-    if (type.name == "URLSearchParams"sv)
+    if (type.name() == "URLSearchParams"sv)
         return true;
-    if (type.name == "DOMException"sv)
+    if (type.name() == "DOMException"sv)
         return true;
 
     return false;
@@ -202,51 +203,51 @@ CppType idl_type_name_to_cpp_type(Type const& type, Interface const& interface)
 {
     if (is_wrappable_type(type)) {
         if (impl_is_wrapper(type)) {
-            return { .name = String::formatted("JS::Handle<{}>", type.name), .sequence_storage_type = SequenceStorageType::MarkedVector };
+            return { .name = String::formatted("JS::Handle<{}>", type.name()), .sequence_storage_type = SequenceStorageType::MarkedVector };
         }
 
-        if (type.nullable)
-            return { .name = String::formatted("RefPtr<{}>", type.name), .sequence_storage_type = SequenceStorageType::Vector };
+        if (type.is_nullable())
+            return { .name = String::formatted("RefPtr<{}>", type.name()), .sequence_storage_type = SequenceStorageType::Vector };
 
-        return { .name = String::formatted("NonnullRefPtr<{}>", type.name), .sequence_storage_type = SequenceStorageType::Vector };
+        return { .name = String::formatted("NonnullRefPtr<{}>", type.name()), .sequence_storage_type = SequenceStorageType::Vector };
     }
 
     if (type.is_string())
         return { .name = "String", .sequence_storage_type = SequenceStorageType::Vector };
 
-    if (type.name == "double" && !type.nullable)
+    if (type.name() == "double" && !type.is_nullable())
         return { .name = "double", .sequence_storage_type = SequenceStorageType::Vector };
 
-    if (type.name == "float" && !type.nullable)
+    if (type.name() == "float" && !type.is_nullable())
         return { .name = "float", .sequence_storage_type = SequenceStorageType::Vector };
 
-    if (type.name == "boolean" && !type.nullable)
+    if (type.name() == "boolean" && !type.is_nullable())
         return { .name = "bool", .sequence_storage_type = SequenceStorageType::Vector };
 
-    if (type.name == "unsigned long" && !type.nullable)
+    if (type.name() == "unsigned long" && !type.is_nullable())
         return { .name = "u32", .sequence_storage_type = SequenceStorageType::Vector };
 
-    if (type.name == "unsigned short" && !type.nullable)
+    if (type.name() == "unsigned short" && !type.is_nullable())
         return { .name = "u16", .sequence_storage_type = SequenceStorageType::Vector };
 
-    if (type.name == "long long" && !type.nullable)
+    if (type.name() == "long long" && !type.is_nullable())
         return { .name = "i64", .sequence_storage_type = SequenceStorageType::Vector };
 
-    if (type.name == "unsigned long long" && !type.nullable)
+    if (type.name() == "unsigned long long" && !type.is_nullable())
         return { .name = "u64", .sequence_storage_type = SequenceStorageType::Vector };
 
-    if (type.name == "long" && !type.nullable)
+    if (type.name() == "long" && !type.is_nullable())
         return { .name = "i32", .sequence_storage_type = SequenceStorageType::Vector };
 
-    if (type.name == "any")
+    if (type.name() == "any")
         return { .name = "JS::Value", .sequence_storage_type = SequenceStorageType::MarkedVector };
 
-    if (type.name == "BufferSource")
+    if (type.name() == "BufferSource")
         return { .name = "JS::Handle<JS::Object>", .sequence_storage_type = SequenceStorageType::MarkedVector };
 
-    if (type.name == "sequence") {
+    if (type.name() == "sequence") {
         auto& parameterized_type = verify_cast<ParameterizedType>(type);
-        auto& sequence_type = parameterized_type.parameters.first();
+        auto& sequence_type = parameterized_type.parameters().first();
         auto sequence_cpp_type = idl_type_name_to_cpp_type(sequence_type, interface);
         auto storage_type_name = sequence_storage_type_to_cpp_storage_type_name(sequence_cpp_type.sequence_storage_type);
 
@@ -256,10 +257,10 @@ CppType idl_type_name_to_cpp_type(Type const& type, Interface const& interface)
         return { .name = String::formatted("{}<{}>", storage_type_name, sequence_cpp_type.name), .sequence_storage_type = SequenceStorageType::Vector };
     }
 
-    if (type.name == "record") {
+    if (type.name() == "record") {
         auto& parameterized_type = verify_cast<ParameterizedType>(type);
-        auto& record_key_type = parameterized_type.parameters[0];
-        auto& record_value_type = parameterized_type.parameters[1];
+        auto& record_key_type = parameterized_type.parameters()[0];
+        auto& record_value_type = parameterized_type.parameters()[1];
         auto record_key_cpp_type = idl_type_name_to_cpp_type(record_key_type, interface);
         auto record_value_cpp_type = idl_type_name_to_cpp_type(record_value_type, interface);
 
@@ -271,14 +272,14 @@ CppType idl_type_name_to_cpp_type(Type const& type, Interface const& interface)
         return { .name = union_type_to_variant(union_type, interface), .sequence_storage_type = SequenceStorageType::Vector };
     }
 
-    if (!type.nullable) {
+    if (!type.is_nullable()) {
         for (auto& dictionary : interface.dictionaries) {
-            if (type.name == dictionary.key)
-                return { .name = type.name, .sequence_storage_type = SequenceStorageType::Vector };
+            if (type.name() == dictionary.key)
+                return { .name = type.name(), .sequence_storage_type = SequenceStorageType::Vector };
         }
     }
 
-    dbgln("Unimplemented type for idl_type_name_to_cpp_type: {}{}", type.name, type.nullable ? "?" : "");
+    dbgln("Unimplemented type for idl_type_name_to_cpp_type: {}{}", type.name(), type.is_nullable() ? "?" : "");
     TODO();
 }
 
@@ -366,11 +367,11 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
     scoped_generator.set("js_name", js_name);
     scoped_generator.set("js_suffix", js_suffix);
     scoped_generator.set("legacy_null_to_empty_string", legacy_null_to_empty_string ? "true" : "false");
-    scoped_generator.set("parameter.type.name", parameter.type->name);
-    if (parameter.type->name == "Window")
+    scoped_generator.set("parameter.type.name", parameter.type->name());
+    if (parameter.type->name() == "Window")
         scoped_generator.set("wrapper_name", "HTML::Window");
     else {
-        scoped_generator.set("wrapper_name", String::formatted("{}Wrapper", parameter.type->name));
+        scoped_generator.set("wrapper_name", String::formatted("{}Wrapper", parameter.type->name()));
     }
 
     if (optional_default_value.has_value())
@@ -389,7 +390,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
     }
 )~~~");
         } else if (!optional) {
-            if (!parameter.type->nullable) {
+            if (!parameter.type->is_nullable()) {
                 scoped_generator.append(R"~~~(
     String @cpp_name@;
     if (@js_name@@js_suffix@.is_null() && @legacy_null_to_empty_string@) {
@@ -414,7 +415,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
         else
             @cpp_name@ = TRY(@js_name@@js_suffix@.to_string(vm));
     })~~~");
-            if (optional_default_value.has_value() && (!parameter.type->nullable || optional_default_value.value() != "null")) {
+            if (optional_default_value.has_value() && (!parameter.type->is_nullable() || optional_default_value.value() != "null")) {
                 scoped_generator.append(R"~~~( else {
         @cpp_name@ = @parameter.optional_default_value@;
     }
@@ -424,15 +425,15 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
 )~~~");
             }
         }
-    } else if (parameter.type->name.is_one_of("EventListener", "NodeFilter")) {
+    } else if (parameter.type->name().is_one_of("EventListener", "NodeFilter")) {
         // FIXME: Replace this with support for callback interfaces. https://heycam.github.io/webidl/#idl-callback-interface
 
-        if (parameter.type->name == "EventListener")
+        if (parameter.type->name() == "EventListener")
             scoped_generator.set("cpp_type", "IDLEventListener");
         else
-            scoped_generator.set("cpp_type", parameter.type->name);
+            scoped_generator.set("cpp_type", parameter.type->name());
 
-        if (parameter.type->nullable) {
+        if (parameter.type->is_nullable()) {
             scoped_generator.append(R"~~~(
     @cpp_type@* @cpp_name@ = nullptr;
     if (!@js_name@@js_suffix@.is_nullish()) {
@@ -453,7 +454,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
 )~~~");
         }
     } else if (IDL::is_wrappable_type(*parameter.type)) {
-        if (!parameter.type->nullable) {
+        if (!parameter.type->is_nullable()) {
             if (!optional) {
                 scoped_generator.append(R"~~~(
     if (!@js_name@@js_suffix@.is_object() || !is<@wrapper_name@>(@js_name@@js_suffix@.as_object()))
@@ -483,7 +484,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
     }
 )~~~");
         }
-    } else if (parameter.type->name == "double" || parameter.type->name == "float") {
+    } else if (parameter.type->name() == "double" || parameter.type->name() == "float") {
         if (!optional) {
             scoped_generator.append(R"~~~(
     @parameter.type.name@ @cpp_name@ = TRY(@js_name@@js_suffix@.to_double(vm));
@@ -512,7 +513,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
 )~~~");
             }
         }
-    } else if (parameter.type->name == "boolean") {
+    } else if (parameter.type->name() == "boolean") {
         if (!optional || optional_default_value.has_value()) {
             scoped_generator.append(R"~~~(
     bool @cpp_name@;
@@ -536,7 +537,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
         @cpp_name@ = @parameter.optional_default_value@;
 )~~~");
         }
-    } else if (parameter.type->name == "unsigned long") {
+    } else if (parameter.type->name() == "unsigned long") {
         if (!optional || optional_default_value.has_value()) {
             scoped_generator.append(R"~~~(
     u32 @cpp_name@;
@@ -560,7 +561,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
         @cpp_name@ = @parameter.optional_default_value@UL;
 )~~~");
         }
-    } else if (parameter.type->name == "unsigned short") {
+    } else if (parameter.type->name() == "unsigned short") {
         if (!optional || optional_default_value.has_value()) {
             scoped_generator.append(R"~~~(
     u16 @cpp_name@;
@@ -584,7 +585,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
         @cpp_name@ = @parameter.optional_default_value@;
 )~~~");
         }
-    } else if (parameter.type->name == "long") {
+    } else if (parameter.type->name() == "long") {
         if (!optional || optional_default_value.has_value()) {
             scoped_generator.append(R"~~~(
     i32 @cpp_name@;
@@ -608,7 +609,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
         @cpp_name@ = @parameter.optional_default_value@L;
 )~~~");
         }
-    } else if (parameter.type->name == "long long") {
+    } else if (parameter.type->name() == "long long") {
         if (!optional || optional_default_value.has_value()) {
             scoped_generator.append(R"~~~(
     i64 @cpp_name@;
@@ -632,7 +633,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
         @cpp_name@ = @parameter.optional_default_value@L;
 )~~~");
         }
-    } else if (parameter.type->name == "Promise") {
+    } else if (parameter.type->name() == "Promise") {
         // NOTE: It's not clear to me where the implicit wrapping of non-Promise values in a resolved
         // Promise is defined in the spec; https://webidl.spec.whatwg.org/#idl-promise doesn't say
         // anything of this sort. Both Gecko and Blink do it, however, so I'm sure it's correct.
@@ -644,7 +645,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
     }
     auto @cpp_name@ = JS::make_handle(&static_cast<JS::Promise&>(@js_name@@js_suffix@.as_object()));
 )~~~");
-    } else if (parameter.type->name == "BufferSource") {
+    } else if (parameter.type->name() == "BufferSource") {
         scoped_generator.append(R"~~~(
     if (!@js_name@@js_suffix@.is_object() || !(is<JS::TypedArrayBase>(@js_name@@js_suffix@.as_object()) || is<JS::ArrayBuffer>(@js_name@@js_suffix@.as_object()) || is<JS::DataView>(@js_name@@js_suffix@.as_object())))
         return vm.throw_completion<JS::TypeError>(JS::ErrorType::NotAnObjectOfType, "@parameter.type.name@");
@@ -652,7 +653,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
     // TODO: Should we make this a Variant?
     auto @cpp_name@ = JS::make_handle(&@js_name@@js_suffix@.as_object());
 )~~~");
-    } else if (parameter.type->name == "any") {
+    } else if (parameter.type->name() == "any") {
         if (!optional) {
             scoped_generator.append(R"~~~(
     auto @cpp_name@ = @js_name@@js_suffix@;
@@ -679,9 +680,9 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
                 }
             }
         }
-    } else if (interface.enumerations.contains(parameter.type->name)) {
+    } else if (interface.enumerations.contains(parameter.type->name())) {
         auto enum_generator = scoped_generator.fork();
-        auto& enumeration = interface.enumerations.find(parameter.type->name)->value;
+        auto& enumeration = interface.enumerations.find(parameter.type->name())->value;
         StringView enum_member_name;
         if (optional_default_value.has_value()) {
             VERIFY(optional_default_value->length() >= 2 && (*optional_default_value)[0] == '"' && (*optional_default_value)[optional_default_value->length() - 1] == '"');
@@ -737,7 +738,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
     }
 )~~~");
         }
-    } else if (interface.dictionaries.contains(parameter.type->name)) {
+    } else if (interface.dictionaries.contains(parameter.type->name())) {
         if (optional_default_value.has_value() && optional_default_value != "{}")
             TODO();
         auto dictionary_generator = scoped_generator.fork();
@@ -747,7 +748,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
 
     @parameter.type.name@ @cpp_name@ {};
 )~~~");
-        auto* current_dictionary = &interface.dictionaries.find(parameter.type->name)->value;
+        auto* current_dictionary = &interface.dictionaries.find(parameter.type->name())->value;
         while (true) {
             for (auto& member : current_dictionary->members) {
                 dictionary_generator.set("member_key", member.name);
@@ -780,11 +781,11 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
             VERIFY(interface.dictionaries.contains(current_dictionary->parent_name));
             current_dictionary = &interface.dictionaries.find(current_dictionary->parent_name)->value;
         }
-    } else if (interface.callback_functions.contains(parameter.type->name)) {
+    } else if (interface.callback_functions.contains(parameter.type->name())) {
         // https://webidl.spec.whatwg.org/#es-callback-function
 
         auto callback_function_generator = scoped_generator.fork();
-        auto& callback_function = interface.callback_functions.find(parameter.type->name)->value;
+        auto& callback_function = interface.callback_functions.find(parameter.type->name())->value;
 
         // An ECMAScript value V is converted to an IDL callback function type value by running the following algorithm:
         // 1. If the result of calling IsCallable(V) is false and the conversion to an IDL value is not being performed due to V being assigned to an attribute whose type is a nullable callback function that is annotated with [LegacyTreatNonObjectAsNull], then throw a TypeError.
@@ -806,7 +807,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
     auto @cpp_name@ = vm.heap().allocate_without_realm<CallbackType>(@js_name@@js_suffix@.as_object(), HTML::incumbent_settings_object());
 )~~~");
         }
-    } else if (parameter.type->name == "sequence") {
+    } else if (parameter.type->name() == "sequence") {
         // https://webidl.spec.whatwg.org/#es-sequence
 
         auto sequence_generator = scoped_generator.fork();
@@ -820,7 +821,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
         // 4. Return the result of creating a sequence from V and method.
 
         if (optional) {
-            auto sequence_cpp_type = idl_type_name_to_cpp_type(parameterized_type.parameters.first(), interface);
+            auto sequence_cpp_type = idl_type_name_to_cpp_type(parameterized_type.parameters().first(), interface);
             sequence_generator.set("sequence.type", sequence_cpp_type.name);
             sequence_generator.set("sequence.storage_type", sequence_storage_type_to_cpp_storage_type_name(sequence_cpp_type.sequence_storage_type));
 
@@ -871,7 +872,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
     }
 )~~~");
         }
-    } else if (parameter.type->name == "record") {
+    } else if (parameter.type->name() == "record") {
         // https://webidl.spec.whatwg.org/#es-record
 
         auto record_generator = scoped_generator.fork();
@@ -879,10 +880,10 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
         record_generator.set("recursion_depth", String::number(recursion_depth));
 
         // A record can only have two types: key type and value type.
-        VERIFY(parameterized_type.parameters.size() == 2);
+        VERIFY(parameterized_type.parameters().size() == 2);
 
         // A record only allows the key to be a string.
-        VERIFY(parameterized_type.parameters[0].is_string());
+        VERIFY(parameterized_type.parameters()[0].is_string());
 
         // An ECMAScript value O is converted to an IDL record<K, V> value as follows:
         // 1. If Type(O) is not Object, throw a TypeError.
@@ -925,7 +926,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
             continue;
 )~~~");
 
-        IDL::Parameter key_parameter { .type = parameterized_type.parameters[0], .name = acceptable_cpp_name, .optional_default_value = {}, .extended_attributes = {} };
+        IDL::Parameter key_parameter { .type = parameterized_type.parameters()[0], .name = acceptable_cpp_name, .optional_default_value = {}, .extended_attributes = {} };
         generate_to_cpp(record_generator, key_parameter, "key", String::number(recursion_depth), String::formatted("typed_key{}", recursion_depth), interface, false, false, {}, false, recursion_depth + 1);
 
         record_generator.append(R"~~~(
@@ -933,7 +934,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
 )~~~");
 
         // FIXME: Record value types should be TypeWithExtendedAttributes, which would allow us to get [LegacyNullToEmptyString] here.
-        IDL::Parameter value_parameter { .type = parameterized_type.parameters[1], .name = acceptable_cpp_name, .optional_default_value = {}, .extended_attributes = {} };
+        IDL::Parameter value_parameter { .type = parameterized_type.parameters()[1], .name = acceptable_cpp_name, .optional_default_value = {}, .extended_attributes = {} };
         generate_to_cpp(record_generator, value_parameter, "value", String::number(recursion_depth), String::formatted("typed_value{}", recursion_depth), interface, false, false, {}, false, recursion_depth + 1);
 
         record_generator.append(R"~~~(
@@ -956,7 +957,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
         RefPtr<Type> dictionary_type;
         for (auto& dictionary : interface.dictionaries) {
             for (auto& type : types) {
-                if (type.name == dictionary.key) {
+                if (type.name() == dictionary.key) {
                     dictionary_type = type;
                     break;
                 }
@@ -968,7 +969,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
 
         if (dictionary_type) {
             auto dictionary_generator = union_generator.fork();
-            dictionary_generator.set("dictionary.type", dictionary_type->name);
+            dictionary_generator.set("dictionary.type", dictionary_type->name());
 
             // The lambda must take the JS::Value to convert as a parameter instead of capturing it in order to support union types being variadic.
             dictionary_generator.append(R"~~~(
@@ -1030,7 +1031,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
 
         bool includes_object = false;
         for (auto& type : types) {
-            if (type.name == "object") {
+            if (type.name() == "object") {
                 includes_object = true;
                 break;
             }
@@ -1062,7 +1063,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
                     continue;
 
                 auto union_platform_object_type_generator = union_generator.fork();
-                union_platform_object_type_generator.set("platform_object_type", String::formatted("{}Wrapper", type.name));
+                union_platform_object_type_generator.set("platform_object_type", String::formatted("{}Wrapper", type.name()));
                 auto cpp_type = IDL::idl_type_name_to_cpp_type(type, interface);
                 union_platform_object_type_generator.set("refptr_type", cpp_type.name);
 
@@ -1087,7 +1088,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
         // 6. If Type(V) is Object and V has an [[ArrayBufferData]] internal slot, then
         //    1. If types includes ArrayBuffer, then return the result of converting V to ArrayBuffer.
         for (auto& type : types) {
-            if (type.name == "BufferSource") {
+            if (type.name() == "BufferSource") {
                 union_generator.append(R"~~~(
             if (is<JS::ArrayBuffer>(@js_name@@js_suffix@_object))
                 return JS::make_handle(@js_name@@js_suffix@_object);
@@ -1117,7 +1118,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
         //     1. If types includes a sequence type, then:
         RefPtr<IDL::ParameterizedType> sequence_type;
         for (auto& type : types) {
-            if (type.name == "sequence") {
+            if (type.name() == "sequence") {
                 sequence_type = verify_cast<IDL::ParameterizedType>(type);
                 break;
             }
@@ -1157,7 +1158,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
         // 4. If types includes a record type, then return the result of converting V to that record type.
         RefPtr<IDL::ParameterizedType> record_type;
         for (auto& type : types) {
-            if (type.name == "record") {
+            if (type.name() == "record") {
                 record_type = verify_cast<IDL::ParameterizedType>(type);
                 break;
             }
@@ -1190,7 +1191,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
         //     1. If types includes boolean, then return the result of converting V to boolean.
         bool includes_boolean = false;
         for (auto& type : types) {
-            if (type.name == "boolean") {
+            if (type.name() == "boolean") {
                 includes_boolean = true;
                 break;
             }
@@ -1232,7 +1233,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
         //     1. If types includes bigint, then return the result of converting V to bigint
         bool includes_bigint = false;
         for (auto& type : types) {
-            if (type.name == "bigint") {
+            if (type.name() == "bigint") {
                 includes_bigint = true;
                 break;
             }
@@ -1367,7 +1368,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
     )~~~");
         }
     } else {
-        dbgln("Unimplemented JS-to-C++ conversion: {}", parameter.type->name);
+        dbgln("Unimplemented JS-to-C++ conversion: {}", parameter.type->name());
         VERIFY_NOT_REACHED();
     }
 }
@@ -1427,7 +1428,7 @@ void IDL::ParameterizedType::generate_sequence_from_iterable(SourceGenerator& ge
     sequence_generator.set("iterable_cpp_name", iterable_cpp_name);
     sequence_generator.set("iterator_method_cpp_name", iterator_method_cpp_name);
     sequence_generator.set("recursion_depth", String::number(recursion_depth));
-    auto sequence_cpp_type = idl_type_name_to_cpp_type(parameters.first(), interface);
+    auto sequence_cpp_type = idl_type_name_to_cpp_type(parameters().first(), interface);
     sequence_generator.set("sequence.type", sequence_cpp_type.name);
     sequence_generator.set("sequence.storage_type", sequence_storage_type_to_cpp_storage_type_name(sequence_cpp_type.sequence_storage_type));
 
@@ -1465,7 +1466,7 @@ void IDL::ParameterizedType::generate_sequence_from_iterable(SourceGenerator& ge
 )~~~");
 
     // FIXME: Sequences types should be TypeWithExtendedAttributes, which would allow us to get [LegacyNullToEmptyString] here.
-    IDL::Parameter parameter { .type = parameters.first(), .name = iterable_cpp_name, .optional_default_value = {}, .extended_attributes = {} };
+    IDL::Parameter parameter { .type = parameters().first(), .name = iterable_cpp_name, .optional_default_value = {}, .extended_attributes = {} };
     generate_to_cpp(sequence_generator, parameter, "next_item", String::number(recursion_depth), String::formatted("sequence_item{}", recursion_depth), interface, false, false, {}, false, recursion_depth);
 
     sequence_generator.append(R"~~~(
@@ -1483,25 +1484,25 @@ static void generate_wrap_statement(SourceGenerator& generator, String const& va
 {
     auto scoped_generator = generator.fork();
     scoped_generator.set("value", value);
-    scoped_generator.set("type", type.name);
+    scoped_generator.set("type", type.name());
     scoped_generator.set("result_expression", result_expression);
     scoped_generator.set("recursion_depth", String::number(recursion_depth));
 
-    if (type.name == "undefined") {
+    if (type.name() == "undefined") {
         scoped_generator.append(R"~~~(
     @result_expression@ JS::js_undefined();
 )~~~");
         return;
     }
 
-    if (type.nullable && !is<UnionType>(type)) {
+    if (type.is_nullable() && !is<UnionType>(type)) {
         if (type.is_string()) {
             scoped_generator.append(R"~~~(
     if (@value@.is_null()) {
         @result_expression@ JS::js_null();
     } else {
 )~~~");
-        } else if (type.name == "sequence") {
+        } else if (type.name() == "sequence") {
             scoped_generator.append(R"~~~(
     if (!@value@.has_value()) {
         @result_expression@ JS::js_null();
@@ -1520,7 +1521,7 @@ static void generate_wrap_statement(SourceGenerator& generator, String const& va
         scoped_generator.append(R"~~~(
     @result_expression@ JS::js_string(vm, @value@);
 )~~~");
-    } else if (type.name == "sequence") {
+    } else if (type.name() == "sequence") {
         // https://webidl.spec.whatwg.org/#es-sequence
         auto& sequence_generic_type = verify_cast<IDL::ParameterizedType>(type);
 
@@ -1528,7 +1529,7 @@ static void generate_wrap_statement(SourceGenerator& generator, String const& va
     auto* new_array@recursion_depth@ = MUST(JS::Array::create(realm, 0));
 )~~~");
 
-        if (!type.nullable) {
+        if (!type.is_nullable()) {
             scoped_generator.append(R"~~~(
     for (size_t i@recursion_depth@ = 0; i@recursion_depth@ < @value@.size(); ++i@recursion_depth@) {
         auto& element@recursion_depth@ = @value@.at(i@recursion_depth@);
@@ -1541,12 +1542,12 @@ static void generate_wrap_statement(SourceGenerator& generator, String const& va
 )~~~");
         }
 
-        if (impl_is_wrapper(sequence_generic_type.parameters.first())) {
+        if (impl_is_wrapper(sequence_generic_type.parameters().first())) {
             scoped_generator.append(R"~~~(
             auto* wrapped_element@recursion_depth@ = &(*element@recursion_depth@);
 )~~~");
         } else {
-            generate_wrap_statement(scoped_generator, String::formatted("element{}", recursion_depth), sequence_generic_type.parameters.first(), interface, String::formatted("auto wrapped_element{} =", recursion_depth), WrappingReference::Yes, recursion_depth + 1);
+            generate_wrap_statement(scoped_generator, String::formatted("element{}", recursion_depth), sequence_generic_type.parameters().first(), interface, String::formatted("auto wrapped_element{} =", recursion_depth), WrappingReference::Yes, recursion_depth + 1);
         }
 
         scoped_generator.append(R"~~~(
@@ -1556,27 +1557,27 @@ static void generate_wrap_statement(SourceGenerator& generator, String const& va
 
     @result_expression@ new_array@recursion_depth@;
 )~~~");
-    } else if (type.name == "boolean" || type.name == "double" || type.name == "float") {
+    } else if (type.name() == "boolean" || type.name() == "double" || type.name() == "float") {
         scoped_generator.append(R"~~~(
     @result_expression@ JS::Value(@value@);
 )~~~");
-    } else if (type.name == "short" || type.name == "long" || type.name == "unsigned short") {
+    } else if (type.name() == "short" || type.name() == "long" || type.name() == "unsigned short") {
         scoped_generator.append(R"~~~(
     @result_expression@ JS::Value((i32)@value@);
 )~~~");
-    } else if (type.name == "unsigned long") {
+    } else if (type.name() == "unsigned long") {
         scoped_generator.append(R"~~~(
     @result_expression@ JS::Value((u32)@value@);
 )~~~");
-    } else if (type.name == "long long") {
+    } else if (type.name() == "long long") {
         scoped_generator.append(R"~~~(
     @result_expression@ JS::Value((double)@value@);
 )~~~");
-    } else if (type.name == "unsigned long long") {
+    } else if (type.name() == "unsigned long long") {
         scoped_generator.append(R"~~~(
     @result_expression@ JS::Value((double)@value@);
 )~~~");
-    } else if (type.name == "Location" || type.name == "Promise" || type.name == "Uint8Array" || type.name == "Uint8ClampedArray" || type.name == "any") {
+    } else if (type.name() == "Location" || type.name() == "Promise" || type.name() == "Uint8Array" || type.name() == "Uint8ClampedArray" || type.name() == "any") {
         scoped_generator.append(R"~~~(
     @result_expression@ @value@;
 )~~~");
@@ -1605,7 +1606,7 @@ static void generate_wrap_statement(SourceGenerator& generator, String const& va
 
             // End of current visit lambda.
             // The last lambda cannot have a trailing comma on the closing brace, unless the type is nullable, where an extra lambda will be generated for the Empty case.
-            if (current_union_type_index != union_types.size() - 1 || type.nullable) {
+            if (current_union_type_index != union_types.size() - 1 || type.is_nullable()) {
                 union_generator.append(R"~~~(
         },
 )~~~");
@@ -1616,7 +1617,7 @@ static void generate_wrap_statement(SourceGenerator& generator, String const& va
             }
         }
 
-        if (type.nullable) {
+        if (type.is_nullable()) {
             union_generator.append(R"~~~(
         [](Empty) -> JS::Value {
             return JS::js_null();
@@ -1628,18 +1629,18 @@ static void generate_wrap_statement(SourceGenerator& generator, String const& va
         union_generator.append(R"~~~(
     );
 )~~~");
-    } else if (interface.enumerations.contains(type.name)) {
+    } else if (interface.enumerations.contains(type.name())) {
         scoped_generator.append(R"~~~(
     @result_expression@ JS::js_string(vm, Bindings::idl_enum_to_string(@value@));
 )~~~");
-    } else if (interface.callback_functions.contains(type.name)) {
+    } else if (interface.callback_functions.contains(type.name())) {
         // https://webidl.spec.whatwg.org/#es-callback-function
 
-        auto& callback_function = interface.callback_functions.find(type.name)->value;
+        auto& callback_function = interface.callback_functions.find(type.name())->value;
 
         // The result of converting an IDL callback function type value to an ECMAScript value is a reference to the same object that the IDL callback function type value represents.
 
-        if (callback_function.is_legacy_treat_non_object_as_null && !type.nullable) {
+        if (callback_function.is_legacy_treat_non_object_as_null && !type.is_nullable()) {
             scoped_generator.append(R"~~~(
   if (!@value@) {
       @result_expression@ JS::js_null();
@@ -1652,7 +1653,7 @@ static void generate_wrap_statement(SourceGenerator& generator, String const& va
   @result_expression@ &@value@->callback;
 )~~~");
         }
-    } else if (interface.dictionaries.contains(type.name)) {
+    } else if (interface.dictionaries.contains(type.name())) {
         // https://webidl.spec.whatwg.org/#es-dictionary
         auto dictionary_generator = scoped_generator.fork();
 
@@ -1660,7 +1661,7 @@ static void generate_wrap_statement(SourceGenerator& generator, String const& va
     auto* dictionary_object@recursion_depth@ = JS::Object::create(realm, realm.intrinsics().object_prototype());
 )~~~");
 
-        auto* current_dictionary = &interface.dictionaries.find(type.name)->value;
+        auto* current_dictionary = &interface.dictionaries.find(type.name())->value;
         while (true) {
             for (auto& member : current_dictionary->members) {
                 dictionary_generator.set("member_key", member.name);
@@ -1687,7 +1688,7 @@ static void generate_wrap_statement(SourceGenerator& generator, String const& va
         dictionary_generator.append(R"~~~(
     @result_expression@ dictionary_object@recursion_depth@;
 )~~~");
-    } else if (type.name == "object") {
+    } else if (type.name() == "object") {
         scoped_generator.append(R"~~~(
     @result_expression@ JS::Value(const_cast<JS::Object*>(@value@));
 )~~~");
@@ -1703,7 +1704,7 @@ static void generate_wrap_statement(SourceGenerator& generator, String const& va
         }
     }
 
-    if (type.nullable && !is<UnionType>(type)) {
+    if (type.is_nullable() && !is<UnionType>(type)) {
         scoped_generator.append(R"~~~(
     }
 )~~~");
@@ -1794,7 +1795,7 @@ static Optional<String> generate_arguments_match_check_for_count(Vector<IDL::Par
         auto argument = String::formatted("arg{}", i);
         StringBuilder condition;
         condition.append('(');
-        if (parameter.type->nullable)
+        if (parameter.type->is_nullable())
             condition.appendff("{}.is_nullish() || ", argument);
         else if (parameter.optional)
             condition.appendff("{}.is_undefined() || ", argument);
@@ -2558,7 +2559,7 @@ JS_DEFINE_NATIVE_FUNCTION(@prototype_class@::@attribute.getter_callback@)
 )~~~");
 
         if (attribute.extended_attributes.contains("Reflect")) {
-            if (attribute.type->name != "boolean") {
+            if (attribute.type->name() != "boolean") {
                 attribute_generator.append(R"~~~(
     auto retval = impl->attribute(HTML::AttributeNames::@attribute.reflect_name@);
 )~~~");
@@ -2592,7 +2593,7 @@ JS_DEFINE_NATIVE_FUNCTION(@prototype_class@::@attribute.setter_callback@)
             generate_to_cpp(generator, attribute, "value", "", "cpp_value", interface, attribute.extended_attributes.contains("LegacyNullToEmptyString"));
 
             if (attribute.extended_attributes.contains("Reflect")) {
-                if (attribute.type->name != "boolean") {
+                if (attribute.type->name() != "boolean") {
                     attribute_generator.append(R"~~~(
     impl->set_attribute(HTML::AttributeNames::@attribute.reflect_name@, cpp_value);
 )~~~");
diff --git a/Meta/Lagom/Tools/CodeGenerators/LibWeb/WrapperGenerator/main.cpp b/Meta/Lagom/Tools/CodeGenerators/LibWeb/WrapperGenerator/main.cpp
index 08d54280c0d..c43d3580a5c 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibWeb/WrapperGenerator/main.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/LibWeb/WrapperGenerator/main.cpp
@@ -112,21 +112,21 @@ int main(int argc, char** argv)
         for (auto& attribute : interface.attributes) {
             dbgln("  {}{}{} {}",
                 attribute.readonly ? "readonly " : "",
-                attribute.type->name,
-                attribute.type->nullable ? "?" : "",
+                attribute.type->name(),
+                attribute.type->is_nullable() ? "?" : "",
                 attribute.name);
         }
 
         dbgln("Functions:");
         for (auto& function : interface.functions) {
             dbgln("  {}{} {}",
-                function.return_type->name,
-                function.return_type->nullable ? "?" : "",
+                function.return_type->name(),
+                function.return_type->is_nullable() ? "?" : "",
                 function.name);
             for (auto& parameter : function.parameters) {
                 dbgln("    {}{} {}",
-                    parameter.type->name,
-                    parameter.type->nullable ? "?" : "",
+                    parameter.type->name(),
+                    parameter.type->is_nullable() ? "?" : "",
                     parameter.name);
             }
         }
@@ -134,13 +134,13 @@ int main(int argc, char** argv)
         dbgln("Static Functions:");
         for (auto& function : interface.static_functions) {
             dbgln("  static {}{} {}",
-                function.return_type->name,
-                function.return_type->nullable ? "?" : "",
+                function.return_type->name(),
+                function.return_type->is_nullable() ? "?" : "",
                 function.name);
             for (auto& parameter : function.parameters) {
                 dbgln("    {}{} {}",
-                    parameter.type->name,
-                    parameter.type->nullable ? "?" : "",
+                    parameter.type->name(),
+                    parameter.type->is_nullable() ? "?" : "",
                     parameter.name);
             }
         }
diff --git a/Userland/Libraries/LibIDL/CMakeLists.txt b/Userland/Libraries/LibIDL/CMakeLists.txt
index 6c36da7885a..b5e3b48b710 100644
--- a/Userland/Libraries/LibIDL/CMakeLists.txt
+++ b/Userland/Libraries/LibIDL/CMakeLists.txt
@@ -1,5 +1,6 @@
 set(SOURCES
     IDLParser.cpp
+    Types.cpp
 )
 
 serenity_lib(LibIDL idl)
diff --git a/Userland/Libraries/LibIDL/IDLParser.cpp b/Userland/Libraries/LibIDL/IDLParser.cpp
index 7b4d4ba9194..1d5fbb2248d 100644
--- a/Userland/Libraries/LibIDL/IDLParser.cpp
+++ b/Userland/Libraries/LibIDL/IDLParser.cpp
@@ -403,7 +403,7 @@ void Parser::parse_getter(HashMap<String, String>& extended_attributes, Interfac
 
     auto& identifier = function.parameters.first();
 
-    if (identifier.type->nullable)
+    if (identifier.type->is_nullable())
         report_parsing_error("identifier's type must not be nullable."sv, filename, input, lexer.tell());
 
     if (identifier.optional)
@@ -411,18 +411,18 @@ void Parser::parse_getter(HashMap<String, String>& extended_attributes, Interfac
 
     // FIXME: Disallow variadic functions once they're supported.
 
-    if (identifier.type->name == "DOMString") {
+    if (identifier.type->name() == "DOMString") {
         if (interface.named_property_getter.has_value())
             report_parsing_error("An interface can only have one named property getter."sv, filename, input, lexer.tell());
 
         interface.named_property_getter = move(function);
-    } else if (identifier.type->name == "unsigned long") {
+    } else if (identifier.type->name() == "unsigned long") {
         if (interface.indexed_property_getter.has_value())
             report_parsing_error("An interface can only have one indexed property getter."sv, filename, input, lexer.tell());
 
         interface.indexed_property_getter = move(function);
     } else {
-        report_parsing_error(String::formatted("Named/indexed property getter's identifier's type must be either 'DOMString' or 'unsigned long', got '{}'.", identifier.type->name), filename, input, lexer.tell());
+        report_parsing_error(String::formatted("Named/indexed property getter's identifier's type must be either 'DOMString' or 'unsigned long', got '{}'.", identifier.type->name()), filename, input, lexer.tell());
     }
 }
 
@@ -437,7 +437,7 @@ void Parser::parse_setter(HashMap<String, String>& extended_attributes, Interfac
 
     auto& identifier = function.parameters.first();
 
-    if (identifier.type->nullable)
+    if (identifier.type->is_nullable())
         report_parsing_error("identifier's type must not be nullable."sv, filename, input, lexer.tell());
 
     if (identifier.optional)
@@ -445,7 +445,7 @@ void Parser::parse_setter(HashMap<String, String>& extended_attributes, Interfac
 
     // FIXME: Disallow variadic functions once they're supported.
 
-    if (identifier.type->name == "DOMString") {
+    if (identifier.type->name() == "DOMString") {
         if (interface.named_property_setter.has_value())
             report_parsing_error("An interface can only have one named property setter."sv, filename, input, lexer.tell());
 
@@ -453,7 +453,7 @@ void Parser::parse_setter(HashMap<String, String>& extended_attributes, Interfac
             report_parsing_error("A named property setter must be accompanied by a named property getter."sv, filename, input, lexer.tell());
 
         interface.named_property_setter = move(function);
-    } else if (identifier.type->name == "unsigned long") {
+    } else if (identifier.type->name() == "unsigned long") {
         if (interface.indexed_property_setter.has_value())
             report_parsing_error("An interface can only have one indexed property setter."sv, filename, input, lexer.tell());
 
@@ -462,7 +462,7 @@ void Parser::parse_setter(HashMap<String, String>& extended_attributes, Interfac
 
         interface.indexed_property_setter = move(function);
     } else {
-        report_parsing_error(String::formatted("Named/indexed property setter's identifier's type must be either 'DOMString' or 'unsigned long', got '{}'.", identifier.type->name), filename, input, lexer.tell());
+        report_parsing_error(String::formatted("Named/indexed property setter's identifier's type must be either 'DOMString' or 'unsigned long', got '{}'.", identifier.type->name()), filename, input, lexer.tell());
     }
 }
 
@@ -477,7 +477,7 @@ void Parser::parse_deleter(HashMap<String, String>& extended_attributes, Interfa
 
     auto& identifier = function.parameters.first();
 
-    if (identifier.type->nullable)
+    if (identifier.type->is_nullable())
         report_parsing_error("identifier's type must not be nullable."sv, filename, input, lexer.tell());
 
     if (identifier.optional)
@@ -485,7 +485,7 @@ void Parser::parse_deleter(HashMap<String, String>& extended_attributes, Interfa
 
     // FIXME: Disallow variadic functions once they're supported.
 
-    if (identifier.type->name == "DOMString") {
+    if (identifier.type->name() == "DOMString") {
         if (interface.named_property_deleter.has_value())
             report_parsing_error("An interface can only have one named property deleter."sv, filename, input, lexer.tell());
 
@@ -494,7 +494,7 @@ void Parser::parse_deleter(HashMap<String, String>& extended_attributes, Interfa
 
         interface.named_property_deleter = move(function);
     } else {
-        report_parsing_error(String::formatted("Named property deleter's identifier's type must be 'DOMString', got '{}'.", identifier.type->name), filename, input, lexer.tell());
+        report_parsing_error(String::formatted("Named property deleter's identifier's type must be 'DOMString', got '{}'.", identifier.type->name()), filename, input, lexer.tell());
     }
 }
 
@@ -809,18 +809,18 @@ static void resolve_typedef(Interface& interface, NonnullRefPtr<Type>& type, Has
 {
     if (is<ParameterizedType>(*type)) {
         auto parameterized_type = static_ptr_cast<ParameterizedType>(type);
-        auto& parameters = static_cast<Vector<NonnullRefPtr<Type>>&>(parameterized_type->parameters);
+        auto& parameters = static_cast<Vector<NonnullRefPtr<Type>>&>(parameterized_type->parameters());
         for (auto& parameter : parameters)
             resolve_typedef(interface, parameter);
         return;
     }
 
-    auto it = interface.typedefs.find(type->name);
+    auto it = interface.typedefs.find(type->name());
     if (it == interface.typedefs.end())
         return;
-    bool is_nullable = type->nullable;
+    bool nullable = type->is_nullable();
     type = it->value.type;
-    type->nullable = is_nullable;
+    type->set_nullable(nullable);
     if (!extended_attributes)
         return;
     for (auto& attribute : it->value.extended_attributes)
diff --git a/Userland/Libraries/LibIDL/Types.cpp b/Userland/Libraries/LibIDL/Types.cpp
new file mode 100644
index 00000000000..0e8ff7160c5
--- /dev/null
+++ b/Userland/Libraries/LibIDL/Types.cpp
@@ -0,0 +1,31 @@
+/*
+ * Copyright (c) 2022, Sam Atkins <atkinssj@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibIDL/Types.h>
+
+namespace IDL {
+
+ParameterizedType const& Type::as_parameterized() const
+{
+    return verify_cast<ParameterizedType const>(*this);
+}
+
+ParameterizedType& Type::as_parameterized()
+{
+    return verify_cast<ParameterizedType>(*this);
+}
+
+UnionType const& Type::as_union() const
+{
+    return verify_cast<UnionType const>(*this);
+}
+
+UnionType& Type::as_union()
+{
+    return verify_cast<UnionType>(*this);
+}
+
+}
diff --git a/Userland/Libraries/LibIDL/Types.h b/Userland/Libraries/LibIDL/Types.h
index 7dc9783753d..306b14f048d 100644
--- a/Userland/Libraries/LibIDL/Types.h
+++ b/Userland/Libraries/LibIDL/Types.h
@@ -3,6 +3,7 @@
  * Copyright (c) 2021, Linus Groh <linusg@serenityos.org>
  * Copyright (c) 2021, Luke Wilde <lukew@serenityos.org>
  * Copyright (c) 2022, Ali Mohammad Pur <mpfard@serenityos.org>
+ * Copyright (c) 2022, Sam Atkins <atkinssj@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -41,29 +42,63 @@ struct CppType {
     SequenceStorageType sequence_storage_type;
 };
 
-struct Type : public RefCounted<Type> {
-    Type() = default;
+class ParameterizedType;
+class UnionType;
+
+class Type : public RefCounted<Type> {
+public:
+    enum class Kind {
+        Plain, // AKA, Type.
+        Parameterized,
+        Union,
+    };
 
     Type(String name, bool nullable)
-        : name(move(name))
-        , nullable(nullable)
+        : m_kind(Kind::Plain)
+        , m_name(move(name))
+        , m_nullable(nullable)
+    {
+    }
+
+    Type(Kind kind, String name, bool nullable)
+        : m_kind(kind)
+        , m_name(move(name))
+        , m_nullable(nullable)
     {
     }
 
     virtual ~Type() = default;
 
-    String name;
-    bool nullable { false };
-    bool is_string() const { return name.is_one_of("ByteString", "CSSOMString", "DOMString", "USVString"); }
+    Kind kind() const { return m_kind; }
+
+    String const& name() const { return m_name; }
+
+    bool is_nullable() const { return m_nullable; }
+    void set_nullable(bool value) { m_nullable = value; }
+
+    bool is_string() const { return m_name.is_one_of("ByteString", "CSSOMString", "DOMString", "USVString"); }
 
     // https://webidl.spec.whatwg.org/#dfn-integer-type
-    bool is_integer() const { return name.is_one_of("byte", "octet", "short", "unsigned short", "long", "unsigned long", "long long", "unsigned long long"); }
+    bool is_integer() const { return m_name.is_one_of("byte", "octet", "short", "unsigned short", "long", "unsigned long", "long long", "unsigned long long"); }
 
     // https://webidl.spec.whatwg.org/#dfn-numeric-type
-    bool is_numeric() const { return is_integer() || name.is_one_of("float", "unrestricted float", "double", "unrestricted double"); }
+    bool is_numeric() const { return is_integer() || m_name.is_one_of("float", "unrestricted float", "double", "unrestricted double"); }
 
     // https://webidl.spec.whatwg.org/#dfn-primitive-type
-    bool is_primitive() const { return is_numeric() || name.is_one_of("bigint", "boolean"); }
+    bool is_primitive() const { return is_numeric() || m_name.is_one_of("bigint", "boolean"); }
+
+    bool is_parameterized() const { return m_kind == Kind::Parameterized; }
+    ParameterizedType const& as_parameterized() const;
+    ParameterizedType& as_parameterized();
+
+    bool is_union() const { return m_kind == Kind::Union; }
+    UnionType const& as_union() const;
+    UnionType& as_union();
+
+private:
+    Kind m_kind;
+    String m_name;
+    bool m_nullable { false };
 };
 
 struct Parameter {
@@ -143,20 +178,23 @@ struct CallbackFunction {
 
 class Interface;
 
-struct ParameterizedType : public Type {
-    ParameterizedType() = default;
-
+class ParameterizedType : public Type {
+public:
     ParameterizedType(String name, bool nullable, NonnullRefPtrVector<Type> parameters)
-        : Type(move(name), nullable)
-        , parameters(move(parameters))
+        : Type(Kind::Parameterized, move(name), nullable)
+        , m_parameters(move(parameters))
     {
     }
 
     virtual ~ParameterizedType() override = default;
 
-    NonnullRefPtrVector<Type> parameters;
-
     void generate_sequence_from_iterable(SourceGenerator& generator, String const& cpp_name, String const& iterable_cpp_name, String const& iterator_method_cpp_name, IDL::Interface const&, size_t recursion_depth) const;
+
+    NonnullRefPtrVector<Type> const& parameters() const { return m_parameters; }
+    NonnullRefPtrVector<Type>& parameters() { return m_parameters; }
+
+private:
+    NonnullRefPtrVector<Type> m_parameters;
 };
 
 static inline size_t get_shortest_function_length(Vector<Function&> const& overload_set)
@@ -238,18 +276,18 @@ public:
     }
 };
 
-struct UnionType : public Type {
-    UnionType() = default;
-
+class UnionType : public Type {
+public:
     UnionType(String name, bool nullable, NonnullRefPtrVector<Type> member_types)
-        : Type(move(name), nullable)
-        , member_types(move(member_types))
+        : Type(Kind::Union, move(name), nullable)
+        , m_member_types(move(member_types))
     {
     }
 
     virtual ~UnionType() override = default;
 
-    NonnullRefPtrVector<Type> member_types;
+    NonnullRefPtrVector<Type> const& member_types() const { return m_member_types; }
+    NonnullRefPtrVector<Type>& member_types() { return m_member_types; }
 
     // https://webidl.spec.whatwg.org/#dfn-flattened-union-member-types
     NonnullRefPtrVector<Type> flattened_member_types() const
@@ -260,14 +298,14 @@ struct UnionType : public Type {
         NonnullRefPtrVector<Type> types;
 
         // 3. For each member type U of T:
-        for (auto& type : member_types) {
+        for (auto& type : m_member_types) {
             // FIXME: 1. If U is an annotated type, then set U to be the inner type of U.
 
             // 2. If U is a nullable type, then set U to be the inner type of U. (NOTE: Not necessary as nullable is stored with Type and not as a separate struct)
 
             // 3. If U is a union type, then add to S the flattened member types of U.
-            if (is<UnionType>(type)) {
-                auto& union_member_type = verify_cast<UnionType>(type);
+            if (type.is_union()) {
+                auto& union_member_type = type.as_union();
                 types.extend(union_member_type.flattened_member_types());
             } else {
                 // 4. Otherwise, U is not a union type. Add U to S.
@@ -288,9 +326,9 @@ struct UnionType : public Type {
         size_t num_nullable_member_types = 0;
 
         // 3. For each member type U of T:
-        for (auto& type : member_types) {
+        for (auto& type : m_member_types) {
             // 1. If U is a nullable type, then:
-            if (type.nullable) {
+            if (type.is_nullable()) {
                 // 1. Set n to n + 1.
                 ++num_nullable_member_types;
 
@@ -298,8 +336,8 @@ struct UnionType : public Type {
             }
 
             // 2. If U is a union type, then:
-            if (is<UnionType>(type)) {
-                auto& union_member_type = verify_cast<UnionType>(type);
+            if (type.is_union()) {
+                auto& union_member_type = type.as_union();
 
                 // 1. Let m be the number of nullable member types of U.
                 // 2. Set n to n + m.
@@ -322,18 +360,18 @@ struct UnionType : public Type {
     bool includes_undefined() const
     {
         // -> the type is a union type and one of its member types includes undefined.
-        for (auto& type : member_types) {
-            if (is<UnionType>(type)) {
-                auto& union_type = verify_cast<UnionType>(type);
-                if (union_type.includes_undefined())
-                    return true;
-            }
+        for (auto& type : m_member_types) {
+            if (type.is_union() && type.as_union().includes_undefined())
+                return true;
 
-            if (type.name == "undefined"sv)
+            if (type.name() == "undefined"sv)
                 return true;
         }
         return false;
     }
+
+private:
+    NonnullRefPtrVector<Type> m_member_types;
 };
 
 }