Brilliant. Simply brilliant.
This has propelled me into a flurry of thoughts about the things I can do with Perl. Higher Order indeed.
The code is here and there somewhat complicated but the added comments have clarified it somewhat and confirmed suspected code meanings.
It explains a way of using flexibility in your code - I'm not too good in explaining this I'm afraid. But it's one of those reads that make you 'get' things. At least for me.
I'm looking forward to the sequel - maybe a tutorial explaining callbacks, closures and factories? Or who knows, self-modifying code ;)