IsCallable

:::info[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. :::

( excerpt from http://php.net/manual/en/reflectionparameter.iscallable.php )

public function isCallable();

Warning: This function is currently not documented; only its argument list is available.

Returns

• mixed - Returns TRUE if the parameter is callable, FALSE if it is not or NULL on failure.