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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 Pair that meet a supplied condition applied to its keys and values

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

Only keys and values that meet a certain criteria are affected by a call to filterWithKey(), while all values are affected by a call to mapWithKey().

Parameters​

  • (function(int, mixed): bool) $callback - The callback containing the condition to apply to the current Pair keys and values.

Returns​