Forgotten #simplisity . one of my colleagues long time ago show me #forth . It was stack based language with #factorisation principle. With every word you program gets better and better and execution mechanisms was super simple but powerful. You get compiler , interpreter and os in one shot. #forth really help to develop complex systems . In a few years I fail in love with #lisp . It was more complex but as same as #forth was build around simple but single data structure - list .