Immutable

:::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 immutable copy (ImmVector) of the current Vector

public function immutable(): ImmVector<Tv>;

This method is interchangeable with toImmVector().

Returns

• ImmVector<Tv> - An ImmVector copy of the current Vector.

Examples

function expects_immutable(ImmVector<mixed> $iv): void {
  \var_dump($iv);
}

<<__EntryPoint>>
function basic_usage_main(): void {
  $v = Vector {'red', 'green', 'blue', 'yellow'};

  // Get a deep, immutable copy of $v
  $immutable_v = $v->immutable();

  expects_immutable($immutable_v);
}