Very interesting stuff. Apparently this is the implementation: https://github.com/dicpeynado/prolog-in-forth
Thinking about the amount of thought and energy that went into this, back in 1987 -- mostly preinternet, pre-AI. Damn.
I feel really lucky that we get to build on things like this.
There's a great 1986 book "Designing and Programming Personal Expert Systems" by Feucht and Townsend that implements expert systems in Forth (and in the process, much of the capability of Prolog and Lisp).
Ha,you beat me to it! That book was my first thought when I saw this post. I have a copy sitting here on my bookshelf.
Just to expand on how bonkers this book is... they assume that everyone has easy access to a Forth implementation. So they teach you how to build a Lisp on top of it. Then they use the Lisp you just built to build a Prolog. Then, finally, they do what the topic of the book actually is: build a simple expert system on top of that Prolog.
I love it!
To be fair, in the 1980s thanks to the Forth Interest Group (FIG), free implementations of Forth existed for most platforms at a time when most programming languages were commercial products selling for $100 or more (in 1980s dollars). It's still pretty weird, but more understandable with that in mind.