type structure change, part done

include/builtin_identifiers.hpp

@@ -0,0 +1,17 @@
+#pragma once
+
+#include <string>
+
+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";
+
+} // namespace builtin