Contains

:::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. :::

Determines if the specified value is in the current Set

public function contains(
  arraykey $val,
): bool;

Parameters

• arraykey $val

Returns

• bool - true if the specified value is present in the current Set; false otherwise.

Examples

$s = Set {'red', 'green', 'blue', 'yellow'};

// Prints "true", since $s contains "red"
\var_dump($s->contains('red'));

// Prints "false", since $s doesn't contain "blurple"
\var_dump($s->contains('blurple'));