True enough that IPL inspired Lisp (along with Church’s Lambda Calculus), but, to my mind, what is interesting about IPL-* is that the first true AIs and Cognitive Models were written in it/them, esp The Logic Theorist, which was the first heuristic search program, and which actually improved upon proofs by some of the most famous logicians of the time. David Moews has made several of the original IPL Logic Theorist programs run again (although not on this 1620 platfor’. . . Yet!) :: https://news.ycombinator.com/item?id=48116935