Skip to main content

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

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

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

Parameters​

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

Returns​