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vmw

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 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<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.

Parameters​

Returns​

Examples​

<<__EntryPoint>>
async function basic_usage_main(): Awaitable<void> {
  // Map a vector of numbers to half integer half
  // throwing if they can't be divided evenly
  $halves = await \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: ";
      \var_dump($result->getResult());
    } else {
      echo "Failed: ";
      \var_dump($result->getException()->getMessage());
    }
  }
}