Returns an Awaitable of Vector of ResultOrExceptionWrapper after a mapping operation has been applied to each value in the provided Traversable


namespace HH\Asio;

function vmw<Tv, Tr>(
  Traversable<Tv> $inputs,
  (function(Tv):Awaitable<Tr>) $callable,
): Awaitable<Vector<HH\Asio\ResultOrExceptionWrapper<Tr>>>;

This function is similar to vm(), except the Vector in the returned Awaitable contains ResultOrExceptionWrappers instead of raw values.

This function is similar to Vector::map(), but the mapping of the values is done using Awaitables.

This function is called vmw because we are returning a vector, doing a mapping operation and each member of the Vector is wrapped by a ResultOrExceptionWrapper.

$callable must return an Awaitable.

The ResultOrExceptionWrappers in the Vector of the returned Awaitable are not available until you await or join the returned Awaitable.


Return Values



namespace Hack\UserDocumentation\API\Examples\HH\Asio\vmw;

// Map a vector of numbers to half integer half
// throwing if they can't be divided evenly
$halves = \HH\Asio\join(\HH\Asio\vmw(
  Vector { 1, 2, 3, 4 },

  async ($val) ==> {
    if ($val % 2) {
      throw new \Exception("$val is an odd number");
    } else {
      return $val / 2;

foreach($halves as $result) {
  if ($result->isSucceeded()) {
    echo "Success: ";
  } else {
    echo "Failed: ";
Failed: string(18) "1 is an odd number"
Success: int(1)
Failed: string(18) "3 is an odd number"
Success: int(2)