(0.8.0)
A Future represents the return value or uncaught exception from a task, and exposes an API for cancellation.
Ejemplo #1 Example showing Future as return value
<?php
$runtime = new \parallel\Runtime;
$future  = $runtime->run(function(){
    return "World";
});
printf("Hello %s\n", $future->value());
?>
El resultado del ejemplo sería algo similar a:
Hello World
The behaviour of a future also allows it to be used as a simple synchronization point even where the task does not return a value explicitly.
Ejemplo #2 Example showing Future as synchronization point
<?php
$runtime = new \parallel\Runtime;
$future  = $runtime->run(function(){
    echo "in child ";
    for ($i = 0; $i < 500; $i++) {
        if ($i % 10 == 0) {
            echo ".";
        }
    }
    echo " leaving child";
});
$future->value();
echo "\nparent continues\n";
?>
El resultado del ejemplo sería algo similar a:
in child .................................................. leaving child parent continues