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filter_nulls

Note

This is a point-in-time snapshot of the API documentation from January 2026. Going forward, we will not be maintaining a public copy of these references, and recommend users to refer to the built-in signature helpers available in the Hack LSP instead for complete and up-to-date information.

Returns a new keyset containing only non-null values of the given Traversable

namespace HH\Lib\Keyset;

function filter_nulls<Tv as arraykey>(
  Traversable<?Tv> $traversable,
): keyset<Tv>;

Time complexity: O(n) Space complexity: O(n)

Parameters​

Returns​

  • keyset<Tv>

Examples​

$result = Keyset\filter_nulls(vec<int>[1,2,3,4,null, null]);
print_r($result);
//result: keyset[1,2,3,4]

$result = Keyset\filter_nulls(vec[1,2,3,4]);
print_r($result);
//result: keyset[1,2,3,4]

$result = Keyset\filter_nulls(vec[]);
print_r($result);
//result: keyset[]