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takeWhile

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 MutableMap containing the keys and values of the current MutableMap up to but not including the first value that produces false when passed to the specified callback

public function takeWhile(
  (function(Tv): bool) $fn,
): MutableMap<Tk, Tv>;

The returned MutableMap will always be a proper subset of the current MutableMap.

Parameters​

  • (function(Tv): bool) $fn - The callback that is used to determine the stopping condition.

Returns​