DocumentationHackReferenceFunctionHH\Asio\vf

HH\Asio\vf

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

namespace HH\Asio;

function vf<Tk, T>(
  KeyedTraversable<Tk, T, mixed> $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

KeyedTraversable<Tk, T, mixed> $inputs - The KeyedTraversable of values to map.
(function(T): Awaitable<bool>) $callable - The callable containing the Awaitable operation to apply to $inputs.

Returns

Awaitable<Vector<T>> - An Awaitable of Vector after the filtering operation has been applied to the values in $inputs.

Examples

$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