I have no idea, but it's 'small' - though there are still two commercial vendors. I'd guess that Franz still sells into some corporate environments and into government/military/security/... Domains people usually don't hear about and end users might not even know that they are using Lisp. If a Lisp-based graph database powers some customer-relationship application at a telco, then nobody will know that it is Lisp. There is also the myth that some military commander won't let their Lisp Machine application go, because it's the only one that never crashed in their data center. Former Swissair had an expert system to improve seat allocation (IIRC), which they maintained for more than a decade - it's might even still be running in Lisp - nobody would know that it exists and how it works... There are also Lisp applications which monitor and control processes in chemical plants - for the end user it's not visible what this is written in.
A bit out of topic but I remember you mentioned you were working on a lisp book and asked what we would wanna see on it.
Well for me, I'm super curious about compiler development, and I think, in the topic of this thread, maybe a chapter on writing a recursive descent parser for JS? building a transpiler? or using lisp as a intermediary with LLVM IR? somewhere where either DSL || "Code is data" and the true advantages of lisp shine through, and I would love that from an experienced lisper. Also if you could go into some use cases for tunable compilers that are seldom elaborated when that is mentioned as a huge lisp advantage! Thanks for giving the community your time in advance!
>>Imagine your application is a CAD system written in Common Lisp with CLOS (there are and were a bunch of those).
For some one considering seriously writing Lisp as a full time job, are these kind of opportunities still there?
I mean how big is Common Lisp usage these days?