DESCRIBE FUNCTION named_struct;
DESCRIBE FUNCTION EXTENDED named_struct;

EXPLAIN
SELECT named_struct("foo", 1, "bar", 2),
       named_struct("foo", 1, "bar", 2).foo FROM src LIMIT 1;

SELECT named_struct("foo", 1, "bar", 2),
       named_struct("foo", 1, "bar", 2).foo FROM src LIMIT 1;