ComponentsFuture::map

Future::map ​

(PHP 8.6+, True Async 1.0)

php
public function map(callable $map): Future

Transforms the Future result using a callback function. The callback receives the value of the completed Future and returns a new value. Analogous to then() in Promise-based APIs. If the original Future completed with an error, the callback is not invoked, and the error is passed through to the new Future.

Parameters ​

map — the transformation function. Receives the Future result, returns a new value. Signature: function(mixed $value): mixed.

Return value ​

Future — a new Future containing the transformed result.

Examples ​

Example #1 Transforming the result ​

php
<?php

use Async\Future;
use Async\FutureState;

$future = Future::completed(5)
    ->map(fn(int $x) => $x * 2)
    ->map(fn(int $x) => "Result: $x");

echo $future->await(); // Result: 10

Example #2 Chain of transformations for async loading ​

php
<?php

use Async\Future;
use Async\FutureState;

$state  = new FutureState();
$source = new Future($state);

\Async\spawn(function() use ($state) {
    $state->complete(file_get_contents('https://api.example.com/data'));
});

$future = $source
    ->map(fn(string $json) => json_decode($json, true))
    ->map(fn(array $data) => $data['users'])
    ->map(fn(array $users) => count($users));

$count = $future->await();
echo "Number of users: $count\n";

See also ​