Add serializer support

README.md

@@ -163,6 +163,16 @@ $results = Fork::new()
     );
 ```
 
+Finally, return values from child tasks are serialized using PHP's built-in `serialize` method. This means that you can return anything you can normally serialize in PHP, including objects:
+
+```php
+$result = Fork::new()
+    ->run(
+        fn () => new DateTime('2021-01-01'),
+        fn () => new DateTime('2021-01-02'),
+    );
+```
+
 ## Testing
 
 ```bash

src/Task.php

@@ -7,6 +7,8 @@
 
 class Task
 {
+    protected const SERIALIZATION_TOKEN = '[[serialized::';
+
     protected string $name;
 
     protected int $order;
@@ -89,10 +91,14 @@ public function execute(): string | bool
     {
         $output = ($this->callable)();
 
-        return json_encode($output);
+        if (is_string($output)) {
+            return $output;
+        }
+
+        return self::SERIALIZATION_TOKEN . serialize($output);
     }
 
-    public function output(): ?string
+    public function output(): mixed
     {
         foreach ($this->connection->read() as $output) {
             $this->output .= $output;
@@ -102,7 +108,15 @@ public function output(): ?string
 
         $this->triggerSuccessCallback();
 
-        return $this->output;
+        $output = $this->output;
+
+        if (str_starts_with($output, self::SERIALIZATION_TOKEN)) {
+            $output = unserialize(
+                substr($output, strlen(self::SERIALIZATION_TOKEN))
+            );
+        }
+
+        return $output;
     }
 
     public function onSuccess(callable $callback): self

tests/ForkTest.php

@@ -2,6 +2,7 @@
 
 namespace Spatie\Fork\Tests;
 
+use DateTime;
 use PHPUnit\Framework\TestCase;
 use Spatie\Fork\Fork;
 
@@ -141,6 +142,19 @@ public function it_will_not_hang_by_truncating_the_result_when_large_output_is_r
         $this->assertCount(3, $result);
     }
 
+    /** @test */
+    public function it_can_return_objects()
+    {
+        $result = Fork::new()
+            ->run(
+                fn () => new DateTime('2021-01-01'),
+                fn () => new DateTime('2021-01-02'),
+            );
+
+        $this->assertEquals('2021-01-01', $result[0]->format('Y-m-d'));
+        $this->assertEquals('2021-01-02', $result[1]->format('Y-m-d'));
+    }
+
     /** @test */
     public function output_in_after()
     {