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

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

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

Parameters​

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

Returns​