HH\Asio\vf

Returns an Awaitable of Vector after a filtering operation has been applied to each value in the provided KeyedTraversable

Description

namespace HH\Asio;

function vf<Tk, T>(
  KeyedTraversable<Tk, T> $inputs,
  (function(T):Awaitable<bool>) $callable,
): Awaitable<Vector<T>>;

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

This function is called vf because we are returning a vector, and we are doing a filtering operation.

$callable must return an Awaitable of bool.

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

Parameters

Return Values

Examples

<?hh

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

$times = ImmVector {
  100000000, // Sat, 03 Mar 1973 09:46:40
  200000000, // Mon, 03 May 1976 19:33:20
  300000000, // Thu, 05 Jul 1979 05:20:00
  400000000, // Sat, 04 Sep 1982 15:06:40
  500000000, // Tue, 05 Nov 1985 00:53:20
  600000000, // Thu, 05 Jan 1989 10:40:00
  700000000, // Sat, 07 Mar 1992 20:26:40
  800000000, // Tue, 09 May 1995 06:13:20
  900000000, // Thu, 09 Jul 1998 16:00:00
 1000000000, // Sun, 09 Sep 2001 01:46:40
};

// Similar to $times->filter(...)
// But awaits the awaitable result of the callback
// rather than using it directly
$saturdays = \HH\Asio\join(\HH\Asio\vf(
  $times,
  async ($time) ==> (gmdate('w', $time) == 6),
));

foreach($saturdays as $time) {
  echo gmdate('r', $time), "\n";
}
Output
Sat, 03 Mar 1973 09:46:40 +0000
Sat, 04 Sep 1982 15:06:40 +0000
Sat, 07 Mar 1992 20:26:40 +0000