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take

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 the first $n elements of the given Traversable

namespace HH\Lib\Keyset;

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

If there are duplicate values in the Traversable, the keyset may be shorter than the specified length.

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

Time complexity: O(n), where n is $n Space complexity: O(n), where n is $n

Parameters​

Returns​

  • keyset<Tv>

Examples​

$result = Keyset\take(keyset[1,200, 5], 2);
print_r($result);
//result: keyset[1,200]

$result = Keyset\take(keyset[100,2000,3,4], 0);
print_r($result);
//result: keyset[]