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 an ImmVector with the values being the keys of the current Pair

public function keys(): ImmVector<int>;

This method will return an ImmVector with keys 0 and 1, and values 0 and 1, since the keys of a Pair are 0 and 1.

Returns

• ImmVector<int> - an ImmVector containing the integer keys of the current Pair as values.

Examples

$p = Pair {'foo', -1.5};
\var_dump($p->keys());