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filterWithKey

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 an ImmVector containing the values of the current ImmVector that meet a supplied condition applied to its keys and values

public function filterWithKey(
  (function(int, Tv): bool) $callback,
): ImmVector<Tv>;

filterWithKey()'s result contains only values whose key/value pairs satisfy the provided criterion; unlike mapWithKey(), which contains results derived from every key/value pair in the original ImmVector.

Parameters​

  • (function(int, Tv): bool) $callback

Returns​

  • ImmVector<Tv> - An ImmVector containing the values of the current ImmVector for which a user-specified test condition returns true when applied to the corresponding key/value pairs.

Examples​

See Vector::filterWithKey for usage examples.