I use Common Lisp for 'exploratory computing' as they say. It's my go-to language if I want to quickly evaluate an idea. Took me a while to learn, but since acquiring at least modest familiarity, I have less patience with ad-hoc syntax (syntactic sugar) found in in-fix languages and the churn found in many currently popular languages.
SBCL might be the best (in terms of correctness, adherence to the standard, performance of the compiled code, compatibility with existing libraries, tool support) open source compiler for CL. The compiler itself can be compared with commercial offerings (those seem to focus rather on additional libraries and external tools).
On ARM32 however, I do use CCL, as SBCL doesn't support multi-threading on that architecture.
SBCL might be the best (in terms of correctness, adherence to the standard, performance of the compiled code, compatibility with existing libraries, tool support) open source compiler for CL. The compiler itself can be compared with commercial offerings (those seem to focus rather on additional libraries and external tools).
On ARM32 however, I do use CCL, as SBCL doesn't support multi-threading on that architecture.