From Async

:::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 the awaited result of the given Awaitables

namespace HH\Lib\Keyset;

function from_async<Tv as arraykey>(
  Traversable<Awaitable<Tv>> $awaitables,
): Awaitable<keyset<Tv>>;

Time complexity: O(n * a), where a is the complexity of the synchronous portions of each Awaitable Space complexity: O(n)

The IO operations for each Awaitable will happen in parallel.

Parameters

• Traversable<Awaitable<Tv>>$awaitables

Returns

• Awaitable<keyset<Tv>>