If you want stable, try Common Lisp.
What’s the best way to get started with Common Lisp now for a very very experienced programmer?
But I'm the sort of person who shrugs when someone says "this software is not updated anymore, it must be out of date." I say: maybe that's good, cat(1) hasn't been updated much, isn't that good?
And CL is just an absolute joy to develop with. Definitely my "stranded on an island" language.