Keys

:::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. :::

Returns a MutableVector containing the values of the current MutableSet

public function keys(): MutableVector<arraykey>;

Sets don't have keys, so this will return the values.

This method is interchangeable with values().

Returns

• MutableVector<arraykey> - a MutableVector (integer-indexed) containing the values of the current MutableSet.