Fill Keys

:::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 dict where all the given keys map to the given value

namespace HH\Lib\Dict;

function fill_keys<Tk as arraykey, Tv>(
  Traversable<Tk> $keys,
  Tv $value,
): dict<Tk, Tv>;

Time complexity: O(n) Space complexity: O(n)

Parameters

• Traversable<Tk>$keys
• Tv $value

Returns

• dict<Tk, Tv>

Examples

$keys = vec['k1', 'k2', 'k3', 'k4'];
$value = 5;
$dict = Dict\fill_keys($keys, $value);
\print_r($dict);