I don't think they wrote any macros. The language they used is Common Lisp with a special library for programming with relations on top. So they used a DSL lib

I don't think they wrote any macros. The language they used is Common Lisp with a special library for programming with relations on top. So they used a DSL library for relational programming. Something like a Lisp with a kind of in-core database with a rich language for it. That kind of programming is extremely rare.