From Keys 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 dict where each value is the result of calling the given async function on the corresponding key

namespace HH\Lib\Dict;

function from_keys_async<Tk as arraykey, Tv>(
  Traversable<Tk> $keys,
  (function(Tk): Awaitable<Tv>) $async_func,
): Awaitable<dict<Tk, Tv>>;

For non-async functions, see Dict\from_keys().

Time complexity: O(n * f), where f is the complexity of $async_func Space complexity: O(n)

Parameters

• Traversable<Tk>$keys
• (function(Tk): Awaitable<Tv>) $async_func

Returns

• Awaitable<dict<Tk,Tv>>