Any sufficiently advanced...

The famous lisp quote - "Any sufficiently complicated C or Fortran program contains an ad hoc informally-specified bug-ridden slow implementation of half of Common Lisp" - make me think of something else today. Specifically I've been building a system where users enter data, someone else enters rules (which are data) and the system goes away and infers more data and then more things to do. That made me realise this:

"Any sufficiently complicated data rich system, which responds based on rules stored as data contains an ad hoc informally-specified bug-ridden slow implementation of half of Prolog."

Now, I'm not saying about to suddenly jump ship and just start writing prolog everywhere, but it's (to me) a useful realisation.