type structure change, mostly done

include/builtin_types.hpp

@@ -0,0 +1,39 @@
+#pragma once
+
+#include <string>
+
+#include "basic_nodes.hpp"
+
+namespace builtin {
+
+const static std::string TUPLE_IDENTIFIER = "Tuple";
+
+const static std::string VARIANT_IDENTIFIER = "Variant";
+
+const static std::string ARRAY_IDENTIFIER = "Array";
+
+const static std::string OPTIONAL_IDENTIFIER = "Optional";
+
+const static std::string RESULT_IDENTIFIER = "Result";
+
+enum class BuiltinType {
+  TUPLE,
+  VARIANT,
+  ARRAY,
+  OPTIONAL,
+  RESULT,
+  NONE,
+};
+
+inline nodes::Modifier builtin_to_modifier(BuiltinType type) {
+  switch (type) {
+  case BuiltinType::OPTIONAL:
+    return nodes::Modifier::OPTIONAL;
+  case BuiltinType::RESULT:
+    return nodes::Modifier::RESULT;
+  default:
+    return nodes::Modifier::NONE;
+  }
+}
+
+} // namespace builtin