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

public function takeWhile(
  (function(Tv): bool) $callback,
): ImmSet<Tv>;

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

Parameters

• (function(Tv): bool) $callback

Returns

• ImmSet<Tv> - An ImmSet that is a proper subset of the current ImmSet up until the callback returns false.

Examples

See Set::takeWhile for usage examples.