Racket! <a href="https://racket-lang.org/" rel="nofollow">https://racket-lang.org/</a><p>“Whenever an engineer changes one of these programs, we run all the programs through our custom model checker (written in Racket + Rosette)”
“we formally verify the programs — written in a custom Lisp-like programming language — that our nameserver executes when it receives a DNS query”
nice