-- element_at
SELECT element_at(array(1, 2, 3), 2);
+-----------------------------+
|element_at(array(1, 2, 3), 2)|
+-----------------------------+
|                            2|
+-----------------------------+

SELECT element_at(map(1, 'a', 2, 'b'), 2);
+------------------------------+
|element_at(map(1, a, 2, b), 2)|
+------------------------------+
|                             b|
+------------------------------+

-- map
SELECT map(1.0, '2', 3.0, '4');
+--------------------+
| map(1.0, 2, 3.0, 4)|
+--------------------+
|{1.0 -> 2, 3.0 -> 4}|
+--------------------+

-- map_concat
SELECT map_concat(map(1, 'a', 2, 'b'), map(3, 'c'));
+--------------------------------------+
|map_concat(map(1, a, 2, b), map(3, c))|
+--------------------------------------+
|                  {1 -> a, 2 -> b, ...|
+--------------------------------------+

-- map_entries
SELECT map_entries(map(1, 'a', 2, 'b'));
+----------------------------+
|map_entries(map(1, a, 2, b))|
+----------------------------+
|            [{1, a}, {2, b}]|
+----------------------------+

-- map_from_arrays
SELECT map_from_arrays(array(1.0, 3.0), array('2', '4'));
+---------------------------------------------+
|map_from_arrays(array(1.0, 3.0), array(2, 4))|
+---------------------------------------------+
|                         {1.0 -> 2, 3.0 -> 4}|
+---------------------------------------------+

-- map_from_entries
SELECT map_from_entries(array(struct(1, 'a'), struct(2, 'b')));
+---------------------------------------------------+
|map_from_entries(array(struct(1, a), struct(2, b)))|
+---------------------------------------------------+
|                                   {1 -> a, 2 -> b}|
+---------------------------------------------------+

-- map_keys
SELECT map_keys(map(1, 'a', 2, 'b'));
+-------------------------+
|map_keys(map(1, a, 2, b))|
+-------------------------+
|                   [1, 2]|
+-------------------------+

-- map_values
SELECT map_values(map(1, 'a', 2, 'b'));
+---------------------------+
|map_values(map(1, a, 2, b))|
+---------------------------+
|                     [a, b]|
+---------------------------+

-- str_to_map
SELECT str_to_map('a:1,b:2,c:3', ',', ':');
+-----------------------------+
|str_to_map(a:1,b:2,c:3, ,, :)|
+-----------------------------+
|         {a -> 1, b -> 2, ...|
+-----------------------------+

SELECT str_to_map('a');
+-------------------+
|str_to_map(a, ,, :)|
+-------------------+
|        {a -> null}|
+-------------------+