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concat

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 Vector that is the concatenation of the values of the current Vector and the values of the provided Traversable

public function concat<Tu super Tv>(
  Traversable<Tu> $traversable,
): Vector<Tu>;

The returned Vector is created from the values of the current Vector, followed by the values of the provided Traversable.

The returned Vector is a new object; the current Vector is unchanged. Future changes to the current Vector will not affect the returned Vector, and future changes to the returned Vector will not affect the current Vector.

Guide​

Parameters​

Returns​

  • Vector<Tu> - A new Vector containing the values from $traversable concatenated to the values from the current Vector.

Examples​

This example creates new Vectors by concatenating other Traversables. Unlike Vector::addAll() this method returns a new Vector (not a shallow copy).

$v = Vector {'red'};

// Add all the values in a Set
$v1 = $v->concat(Set {'green', 'blue'});

// Add all the values in an array
$v2 = $v1->concat(varray['yellow', 'purple']);

\var_dump($v); // $v contains 'red'
\var_dump($v1); // $v1 contains 'red', 'green', 'blue'
\var_dump($v2); // $v2 contains 'red', 'green', 'blue', 'yellow', 'purple'