[lispm]

Providing patches as compiled code loadable into applications is fairly common (!) in Lisp.

[kazinator]

But usually those patches are already validated. Providing validated patches is one thing; developing them on the live system is another.

[lispm]

You would develop it in some live system anyway. That's the usual way to develop in Lisp. It does not mean that the 'live system' is also a 'production system'.