I found ocaml to be a more flexible alternative -- I can sprinkle printf for quick debugging without having to alter types. (I think this is what you mean by "having to use the IO monad". I didn't work with haskell much, so it's possible there's an easy way around this there.) And stack traces in ocaml are reasonable, though not quite as verbose as python's.

But your point about needing to install extra packages stands for either language.