Lisp books, especially in AI Programming, have implemented various Logics - predicate logic based programming like standard Prolog is just one. Peter Norvig has

Lisp books, especially in AI Programming, have implemented various Logics - predicate logic based programming like standard Prolog is just one. Peter Norvig has a relative extensive example how to implement Prolog and how to compile it. Others concentrate on some other logic calculus. It's not surprising that various books have different depths in showing how to implement various embedded languages. In case of Norvig's implementation, others have used in their application. It has nothing to do with Greenspun at all. Lisp and then Common Lisp was used in many AI programming frameworks and these integrated various paradigms: rule systems, various logics, objects, frames, constraints, semantic networks, fuzzy logic, relational, ... Lisp was explicitly designed for this - there is nothing accidental about it. It is one of the main purposes of Lisp in AI Programming to enable experiments and implementations of various paradigms. That means that these frameworks EXPLICLTY implement something like predicate logics or other logics. These features are advertized and documented. Greenspun claimed that complex C++ programs more or less ACCIDENTALLY implement half of a Lisp implementation, because the large enough implementations need these features: automatic memory management, runtime loading of code, dynamic data structures like lists and trees, runtime scripting, saving and loading of state, configuration of software, a virtual machine, ... These programs implement some random subsets of what a Common Lisp system may provide, but they don't implement Common Lisp or its features directly. Most C++ developers don't know that these features actually exist in Lisp and they don't care. Similar the Java VM implements some stuff one could find in a Smalltalk or Lisp system: virtual machine, code loading, managed memory, calling semantics, ...