There are several well maintained Common Lisp compilers, some of which are paid for and can sustain whole businesses, Clojure is fairly big as niche languages go, and Guile Scheme is used across GNU projects. There’s also some usage of Racket and Scheme in education, and I believe Janet is having success in gaming. So I wouldn’t say Lisp survives by just a slim margin.
Correct. That was bad wording on my part. I meant it in the sense of "it survives at a scale proportional to the fraction of it that is unique".
It used to be that things like GC, REPL, flexible syntax, the cond form etc. made Lisp unique, but these days the list is down mainly to homoiconicity (and an amazing hacker culture).
the image-based REPL, including the interactive debugger, is still unique (matched maybe by Smalltalk), CLOS and the condition system too… pair them with stability, fast implementations, instantaneous compile-time errors and warnings a keystroke away, a Haskell-like type system on top of the language (Coalton), macros… and the whole is still pretty unique.
