I’ve taken various detours along the way into learning and using various other languages. I like several of them quite a bit. I just don’t like them as much as Common Lisp. The pleasure I take in my work is a significant factor in my productivity. Choosing tools that offer me less joy is a cost I prefer not to bear without good reason. That cost often exceeds the advantage I might realize from using some other language. Not always; but often. — Production Lisp in 2020?