Drop

:::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 new keyset containing all except the first $n elements of the given Traversable

namespace HH\Lib\Keyset;

function drop<Tv as arraykey>(
  Traversable<Tv> $traversable,
  int $n,
): keyset<Tv>;

To take only the first $n elements, see Keyset\take().

Time complexity: O(n), where n is the size of $traversable Space complexity: O(n), where n is the size of $traversable

Parameters

• Traversable<Tv>$traversable
• int $n

Returns

• keyset<Tv>

Examples

$result = Keyset\drop(keyset[1,2,3,4,5,6], 3);
print_r($result);
//result: keyset[4,5,6]

$result = Keyset\drop(vec[1,2,3,4,5,6], 0);
print_r($result);
//result: keyset[1,2,3,4,5,6]