declarative function composition - PHP

gistfile1.php

<?php
use \Closure;
class Invokable {
    
    private $closure;
    
    public function __construct(Closure $closure) {
        $this->closure = $closure;
    }
    
    public static function newInstance(Closure $closure) {
        return new self($closure);
    }
    
    public function __invoke($arg) {
        $c = $this->closure;
        return $c($arg);
    }
    
    public function compose(Invokable $inner) {
        $inv = $this;
        return Invokable::newInstance(
            function($i) use ($inv, $inner) {
                return $inv($inner($i));
            }
        );
        return $this;
    }
    
}
$inv1 = Invokable::newInstance(
    function($i) {
        return $i * 2;
    }
);

$inv2 = Invokable::newInstance(
    function($i) {
        return $i + 1;
    }
);

$inv3 = Invokable::newInstance(
    function($i) {
        return $i + 10;
    }
);

$inv = $inv1->compose($inv2)->compose($inv3);

echo ($inv(2));