Zip

:::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. :::

Throws an exception unless the current Set or the Traversable is empty

public function zip<Tu>(
  Traversable<Tu> $traversable,
): Set<HH\nothing>;

Since Sets only support integers or strings as values, we cannot have a Pair as a Set value. So in order to avoid an InvalidArgumentException, either the current Set or the Traversable must be empty so that we actually return an empty Set.

Parameters

• Traversable<Tu>$traversable - The Traversable to use to combine with the elements of the current Set.

Returns

• Set<HH\nothing> - The Set that combines the values of the current Set with the provided Traversable; one of these must be empty or an exception is thrown.

Examples

This example shows that zip won't thrown an Exception if at least one of the current Set or the $traversable is empty:

// The $traversable is empty so the result will be empty
$s = Set {'red', 'green', 'blue', 'yellow'};
$zipped = $s->zip(Vector {});
\var_dump($zipped);

// The Set $s is empty so the result will be empty
$s = Set {};
$zipped = $s->zip(Vector {'My Favorite', 'My Second Favorite'});
\var_dump($zipped);

This example shows that zip will throw an Exception if the result is non-empty:

$s = Set {'red', 'green', 'blue', 'yellow'};
$zipped = $s->zip(Vector {'My Favorite', 'My Second Favorite'});
\var_dump($zipped);