The problem of Lisp is the side-effecting nature of it. There's nothing complex in metaprogramming, if you do it in pure setting. The problems arise when you co

The problem of Lisp is the side-effecting nature of it. There's nothing complex in metaprogramming, if you do it in pure setting. The problems arise when you combine two differently side-effecting pieces of software and Lisp does nothing to prevent that or help there. I won't stop repeat that mantra that side effects and program state are an implicit information channel in a program. This channel is shared by many parts (or parties) inside program and it has some specific implicitly specified protocol of use. Add a piece of software that uses the channel with slightly different protocol as assumption, get ready for all sorts of problems.