Video introduction to Push, a lispy stack-based genetic programming language https://www.youtube.com/watch?v=VGJWlSC0gl4&t=42s
Push still intrigues me. Though I still wonder if an approach that uses a single stack with generics might be more likely to work in an environment as "squishy" as genetic programming than the separate-stacks approach that Push uses. I wrote up some ideas for that here a while ago: https://dustycloud.org/blog/gush-intro/