Slice

:::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 subset of the current Set starting from a given key up to, but not including, the element at the provided length from the starting key

public function slice(
  int $start,
  int $len,
): Set<Tv>;

$start is 0-based. $len is 1-based. So slice(0,2) would return the elements at key 0 and 1.

The returned Set will always be a proper subset of the current Set.

Parameters

• int $start - The starting value in the current Set for the returned Set.
• int $len - The length of the returned Set.

Returns

• Set<Tv> - A Set that is a proper subset of the current Set starting at $start up to but not including the element $start + $len.

Examples

$s = Set {'red', 'green', 'blue', 'yellow'};

// Start at index 1 ('green') and include 3 elements
$s2 = $s->slice(1, 3);

\var_dump($s2);