Future::map

(PHP 8.6+, True Async 1.0)

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

use Async\Future;

$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

use Async\Future;

$future = \Async\async(function() {
    return file_get_contents('https://api.example.com/data');
})
->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";

Documentation