"This just sounds like over-engineering the problem."
Except the problem was never defined. Of the five commercial Lisp applications I've worked on, two are addressing domains (large-scale financial calculations, and a web platform/OS) where using PHP makes absolutely no sense, and the current one (ERP) where PHP was previously attempted and found not to make any sense. All three use basic techniques like closures, markup generation and metaprogramming, and one of them is continuation-based (which I think is a mistake, but opinions differ).
Except the problem was never defined. Of the five commercial Lisp applications I've worked on, two are addressing domains (large-scale financial calculations, and a web platform/OS) where using PHP makes absolutely no sense, and the current one (ERP) where PHP was previously attempted and found not to make any sense. All three use basic techniques like closures, markup generation and metaprogramming, and one of them is continuation-based (which I think is a mistake, but opinions differ).