[qsort]

Sure, more examples are CSP solvers and AMPL. They are all somewhat specific though. I was wondering if it would be possible to make one that's "general purpose" in the same sense you call programming languages "general purpose", i.e. one you'd write application software in.

[UncleMeat]

Datalog would be the closest I can think of. A bunch of static analysis engines are implemented in it.