SELECT name_to_age_map['Bob'] AS bob_age;

cardinality(x) -> bigint

element_at(map(K,V), key) -> V

map() -> map<unknown, unknown>

SELECT map();
-- {}

map(array(K), array(V)) -> map(K,V)

SELECT map(ARRAY[1,3], ARRAY[2,4]);
-- {1 -> 2, 3 -> 4}

map_from_entries(array(row(K,V))) -> map(K,V)

SELECT map_from_entries(ARRAY[(1, 'x'), (2, 'y')]);
-- {1 -> 'x', 2 -> 'y'}

multimap_from_entries(array(row(K,V))) -> map(K,array(V))

SELECT multimap_from_entries(ARRAY[(1, 'x'), (2, 'y'), (1, 'z')]);
-- {1 -> ['x', 'z'], 2 -> ['y']}

map_entries(map(K,V)) -> array(row(K,V))

SELECT map_entries(MAP(ARRAY[1, 2], ARRAY['x', 'y']));
-- [ROW(1, 'x'), ROW(2, 'y')]

map_concat(map1(K,V), map2(K,V), ..., mapN(K,V)) -> map(K,V)

map_filter(map(K,V), function(K,V,boolean)) -> map(K,V)

SELECT map_filter(MAP(ARRAY[], ARRAY[]), (k, v) -> true);
-- {}

SELECT map_filter(MAP(ARRAY[10, 20, 30], ARRAY['a', NULL, 'c']),
                  (k, v) -> v IS NOT NULL);
-- {10 -> a, 30 -> c}

SELECT map_filter(MAP(ARRAY['k1', 'k2', 'k3'], ARRAY[20, 3, 15]),
                  (k, v) -> v > 10);
-- {k1 -> 20, k3 -> 15}

map_keys(x(K,V)) -> array(K)

map_values(x(K,V)) -> array(V)

map_zip_with(map(K,V1), map(K,V2), function(K,V1,V2,V3)) -> map(K,V3)

SELECT map_zip_with(MAP(ARRAY[1, 2, 3], ARRAY['a', 'b', 'c']),
                    MAP(ARRAY[1, 2, 3], ARRAY['d', 'e', 'f']),
                    (k, v1, v2) -> concat(v1, v2));
-- {1 -> ad, 2 -> be, 3 -> cf}

SELECT map_zip_with(MAP(ARRAY['k1', 'k2'], ARRAY[1, 2]),
                    MAP(ARRAY['k2', 'k3'], ARRAY[4, 9]),
                    (k, v1, v2) -> (v1, v2));
-- {k1 -> ROW(1, null), k2 -> ROW(2, 4), k3 -> ROW(null, 9)}

SELECT map_zip_with(MAP(ARRAY['a', 'b', 'c'], ARRAY[1, 8, 27]),
                    MAP(ARRAY['a', 'b', 'c'], ARRAY[1, 2, 3]),
                    (k, v1, v2) -> k || CAST(v1 / v2 AS VARCHAR));
-- {a -> a1, b -> b4, c -> c9}

transform_keys(map(K1,V), function(K1,V,K2)) -> map(K2,V)

SELECT transform_keys(MAP(ARRAY[], ARRAY[]), (k, v) -> k + 1);
-- {}

SELECT transform_keys(MAP(ARRAY [1, 2, 3], ARRAY ['a', 'b', 'c']),
                      (k, v) -> k + 1);
-- {2 -> a, 3 -> b, 4 -> c}

SELECT transform_keys(MAP(ARRAY ['a', 'b', 'c'], ARRAY [1, 2, 3]),
                      (k, v) -> v * v);
-- {1 -> 1, 4 -> 2, 9 -> 3}

SELECT transform_keys(MAP(ARRAY ['a', 'b'], ARRAY [1, 2]),
                      (k, v) -> k || CAST(v as VARCHAR));
-- {a1 -> 1, b2 -> 2}

SELECT transform_keys(MAP(ARRAY [1, 2], ARRAY [1.0, 1.4]),
                      (k, v) -> MAP(ARRAY[1, 2], ARRAY['one', 'two'])[k]);
-- {one -> 1.0, two -> 1.4}

transform_values(map(K,V1), function(K,V1,V2)) -> map(K,V2)

SELECT transform_values(MAP(ARRAY[], ARRAY[]), (k, v) -> v + 1);
-- {}

SELECT transform_values(MAP(ARRAY [1, 2, 3], ARRAY [10, 20, 30]),
                        (k, v) -> v + k);
-- {1 -> 11, 2 -> 22, 3 -> 33}

SELECT transform_values(MAP(ARRAY [1, 2, 3], ARRAY ['a', 'b', 'c']),
                        (k, v) -> k * k);
-- {1 -> 1, 2 -> 4, 3 -> 9}

SELECT transform_values(MAP(ARRAY ['a', 'b'], ARRAY [1, 2]),
                        (k, v) -> k || CAST(v as VARCHAR));
-- {a -> a1, b -> b2}

SELECT transform_values(MAP(ARRAY [1, 2], ARRAY [1.0, 1.4]),
                        (k, v) -> MAP(ARRAY[1, 2], ARRAY['one', 'two'])[k]
                          || '_' || CAST(v AS VARCHAR));
-- {1 -> one_1.0, 2 -> two_1.4}