Mmk

:::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 an Awaitable of Map after a mapping operation has been applied to each key and value in the provided KeyedTraversable

namespace HH\Asio;

function mmk<Tk as arraykey, Tv, Tr>(
  KeyedTraversable<Tk, Tv> $inputs,
  (function(Tk, Tv): Awaitable<Tr>) $callable,
): Awaitable<Map<Tk, Tr>>;

This function is similar to mm(), but passes element keys to the callable as well.

This function is similar to Map::mapWithKey(), but the mapping of the keys and values is done using Awaitables.

This function is called mmk because we are returning a map and doing a a mapping operation that includes keys.

$callable must return an Awaitable.

The keys and values in the Map of the returned Awaitable are not available until you await or join the returned Awaitable.

Parameters

• KeyedTraversable<Tk,Tv> $inputs - The KeyedTraversable of keys and values to map.
• (function(Tk, Tv): Awaitable<Tr>) $callable - The callable containing the Awaitable operation to apply to $inputs.

Returns

• Awaitable<Map<Tk,Tr>> - An Awaitable of Map after the mapping operation has been applied to both the keys and values in $inputs.

Examples

/**
 * Query an arbitrary number of URLs in parallel
 * returning them as a Map of string responses.
 */
async function get_urls(
  \ConstMap<string, string> $urls,
): Awaitable<Map<string, string>> {

  // Await on curl requests in parallel and
  // prepend the request ID index
  return await \HH\Asio\mmk(
    $urls,
    async ($name, $url) ==> {
      $content = await \HH\Asio\curl_exec($url);
      return $name." => ".$content;
    },
  );
}

<<__EntryPoint>>
async function basic_usage_main(): Awaitable<void> {
  $urls = ImmMap {
    'com' => "http://example.com",
    'net' => "http://example.net",
    'org' => "http://example.org",
  };

  $pages = await get_urls($urls);
  foreach ($pages as $page) {
    echo \substr($page, 0, 22).' ... '.\substr($page, -8);
  }
}
```.skipif
// Skip if we don't have an internet connection
if (!\get_headers("www.example.com")) {
  print "skip";
}