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

namespace HH\Asio;

function vm<Tv, Tr>(
  Traversable<Tv> $inputs,
  (function(Tv): Awaitable<Tr>) $callable,
): Awaitable<Vector<Tr>>;

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

This function is called vm because we are returning a vector, and we are doing a mapping operation.

$callable must return an Awaitable.

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




 * Query an arbitrary number of URLs in parallel
 * returning them as a Vector of string responses.
 * Refer to \HH\Asio\v() for a more verbose version of this.
async function get_urls(\ConstVector<string> $urls): Awaitable<Vector<string>> {

  // Invoke \HH\Asio\curl_exec for each URL,
  // then await on each in parallel
  return await \HH\Asio\vm($urls, fun("\HH\Asio\curl_exec"));

$urls = ImmVector {

$pages = \HH\Asio\join(get_urls($urls));
foreach ($pages as $page) {
  echo substr($page, 0, 15).' ... '.substr($page, -8);
<!doctype html> ... </html>
<!doctype html> ... </html>
<!doctype html> ... </html>