One thing I can do in Common Lisp which I can't do (almost) anywhere else (but including Racket) is proper REPL-based interactive development. Specifically, I can update state without needing to recompile my program. For my use case this is unmatched for prototyping.
As regards low-level stuff, this is very implementation specific (which is OK for low-level programming). Specifically, SBCL allows me to write much faster code than Racket. Particularly there does not need to be a speed cap or even penalty for using a high level language.
As regards low-level stuff, this is very implementation specific (which is OK for low-level programming). Specifically, SBCL allows me to write much faster code than Racket. Particularly there does not need to be a speed cap or even penalty for using a high level language.