Skip to main content

mw

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.

Translate a KeyedTraversable of Awaitables into a single Awaitable of Map of key/ResultOrExceptionWrapper pairs

namespace HH\Asio;

function mw<Tk as arraykey, Tv>(
  KeyedTraversable<Tk, Awaitable<Tv>> $awaitables,
): Awaitable<Map<Tk, ResultOrExceptionWrapper<Tv>>>;

This function is the same as m(), but wraps the results into key/ResultOrExceptionWrapper pairs.

This function takes any KeyedTraversable object of Awaitables (i.e., each member of the KeyedTraversable has a value of type Awaitable, likely from a call to a function that returned Awaitable<T>), and transforms those Awaitables into one big Awaitable Map of key/ResultOrExceptionWrapper pairs.

This function is called mw because we are returning a map of Awaitable wrapped into ResultofExceptionWrappers.

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

Parameters​

Returns​

Examples​

async function one(): Awaitable<int> {
  return 1;
}

<<__EntryPoint>>
async function basic_usage_main(): Awaitable<void> {
  $mcr = \MCRouter::createSimple(ImmVector {});

  $handles = \HH\Asio\mw(Map {
    // This will throw an exception, since there's no servers to speak to
    'cache' => $mcr->get("no-such-key"),

    // While this will obviously succeed
    'one' => one(),
  });

  $results = await $handles;
  foreach ($results as $key => $result) {
    if ($result->isSucceeded()) {
      echo "$key Success: ";
      \var_dump($result->getResult());
    } else {
      echo "$key Failed: ";
      \var_dump($result->getException()->getMessage());
    }
  }
}
```.skipif
\Hack\UserDocumentation\API\Examples\MCRouter\skipif();