Allow declaring type synonyms

source/lexer.ll

@@ -67,6 +67,10 @@ array                   {
 of                      {
                             return yy::parser::make_OF(this->location);
                         }
+type                    {
+                            return yy::parser::make_TYPE(this->location);
+                        }
+
 true                    {
                             return yy::parser::make_BOOLEAN(true, this->location);
                         }