Skeleton is ready

app/Kernel/String/Hash.php

@@ -0,0 +1,13 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Kernel\String;
+
+class Hash
+{
+    public static function xxh128(string $value): string
+    {
+        return hash('xxh128', $value);
+    }
+}

app/Kernel/String/Regex.php

@@ -0,0 +1,11 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Kernel\String;
+
+enum Regex: string
+{
+    case Uuid7 = '^[0-9a-f]{8}-[0-9a-f]{4}-7[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$';
+    case Numeric = '^[0-9]+$';
+}

app/Kernel/String/String.php

@@ -0,0 +1,10 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Kernel\String;
+
+enum String: string
+{
+    case Empty = '';
+}