README.md

$upper = pipe('strtoupper');
$rev = $upper->pipe('strrev');

echo $upper('hello');
echo $rev('Hello');
echo pipe('strtoupper', 'strrev')('hello'); 

pipe.php

<?php

interface PipeInterface
{
    public function pipe(callable ...$callbacks): PipeInterface;
    public function process($payload);
}

function pipe(callable ...$callbacks)
{
    return new class(...$callbacks) implements PipeInterface
    {
        private $callbacks;

        public function __construct(callable ...$callbacks)
        {
            $this->callbacks = $callbacks;
        }

        public function pipe(callable ...$callbacks): PipeInterface
        {
            return pipe(...array_merge($this->callbacks, $callbacks));
        }

        public function process($payload)
        {
            return array_reduce($this->callbacks, function ($payload, $callback) {
                return call_user_func($callback, $payload);
            }, $payload);
        }

        public function __invoke($payload)
        {
            return $this->process($payload);
        }
    };
}