Something I am working on...

project_x0.php

<?php

// command-name {name:required} {age:optional:"Jack"} 
// command-name {--name} {--age:required} {--country:optional:USA}

// facade:resolve "Show underlying classes and the corresponding IoC bindings" {query:optional:"Query string":"*"}

listen("say-hello")->act(function($input, $output) {
    $output("Hello, world!");
});

listen("say-name {--name:required:Generic}")->act(function($input, $output) {
    $output("Hello, ".$input("name")); 
});

listen("do-something {age:required} {country:optional:USA} {--save:optional} {--path:required}")
    ->act(function($input, $output) 
    {
        $savePath = $input("save") ? $input("path", "generic/path") : null;
        
        $message = sprintf("%s:%s => %s", $input("age"), $input("country"), $savePath);
        
        $output($message);
    });

go();