gistfile1.php

<?php
function compose($f, $g) {
    return function() use($f, $g) {
        return $f(call_user_func_array($g, func_get_args()));
    };
}

function ctor($class) {
    $reflect = new \ReflectionClass($class);
    return function() use($reflect) {
        return $reflect->newInstanceArgs(func_get_args());
    };
}

$scopeParentID = mapNullable($request->query->get('scope-parent'),
                             compose(ctor('NodeID'), 'intval'));