fn1.php

<?php

declare(strict_types = 1);

function partial(callable $fn, ...$args)
{
    $numReqParams = (new \ReflectionFunction($fn))->getNumberOfRequiredParameters();

    return isset($args[$numReqParams - 1])
        ? $fn(...$args)
        : function (...$restArgs) use ($fn, $args) {
            return partial($fn, ...array_merge($args, $restArgs));
        };
}

function filter(...$args)
{
    return partial(function (callable $fn, array $xss, $flag = 0) {
        return array_filter($xss, $fn, $flag);
    })(...$args);
}

function typeof (...$args)
{
    return partial(function ($type, $value) {
        return $value instanceof $type;
    })(...$args);
}

function head(array $xss)
{
    return [] === $xss
        ? $xss
        : array_values($xss)[0];
}

interface IdInterface
{
}

interface EmailInterface
{
}

interface UserInterface
{
}

interface OrgInterface
{
    public function getName(): string;
}

interface ProfileInterface extends UserInterface
{
    public function getId(): IdInterface;
    public function getName(): string;
    public function getEmail(): EmailInterface;
}

$sergio = new class implements ProfileInterface {
    public function getId(): IdInterface {
        return new class implements IdInterface {
        };
    }
    
    public function getName(): string {
        return 'Sérgio Rafael Siqueira';
    }

    public function getEmail(): EmailInterface {
        return new class implements EmailInterface {
        };
    }
};

$tiago = new class implements UserInterface {
};

$inbep = new class implements OrgInterface {
    public function getName(): string {
        return 'INBEP';
    }
};

var_dump($users = [$sergio, $tiago, $inbep]);

var_dump($justUsers = filter(typeof(UserInterface::class), $users));

var_dump(head(filter(typeof(ProfileInterface::class), $justUsers))->getName());

var_dump(head(filter(typeof(OrgInterface::class), $users))->getName());