It's general purpose. It's a high-level language that has OS-level threading, can be functional/imperative, compiles to machine code, has powerful macros which completely cut down code repetition and allow syntax expansion, can call out to C without compiling wrappers. About the only thing it's missing are coroutines, and even those can be mimicked by macros to some extent. Really, a better question is what can't lisp do. It's probably not the best choice for an embedded device or something like that, or anywhere you need tight control over memory/resources. I'd say it's an extremely decent complement to C in a lot of respects. If you can get passed some of the oddly-named symbols, it's a great language that has made leaps and bounds in the past 10 years as far as third-party libraries and implementation features.