I'd argue Clojure has all 3

Stability - one of Clojure's core tenets.

Low language complexity - not much more than EDN and everything is an expression, plus a few extras like destructuring. Certainly simpler than any other language I have used.

Extensibility - again, one of Clojure's strong points with macros.

As for "Type systems removing the value of a repl" again, I disagree. Repl driven development is as much about exploring the problem than it is writing code.