<?php
class Pipeline
{
    public static function make_pipeline(...$funcs)
    {
        return function($arg) use ($funcs)
        {
            $value = $arg;
            foreach($funcs as $f) {
                $value = $f($value);
            }
            return $value;
        };
    }
}
$fun = Pipeline::make_pipeline(function($x) { return $x * 3; }, function($x) { return $x + 1; },
                          function($x) { return $x / 2; });
echo $fun(3);