Here's what I want: Something with programmer productivity similar to Python, but type-inferred for predictably good execution speed, with more support for func

Here's what I want: Something with programmer productivity similar to Python, but type-inferred for predictably good execution speed, with more support for functional programming style, with green threads preemptively executing in parallel and immutability baked deeply into the whole thing. And then a track record of deployment so the ugly GC and type system edge cases are ironed out and libraries are plentiful. Elixir/Erlang will probably never be fast enough, Go didn't commit to immutability and its functional programming support is minimal, Rust could have all that but it's too low-level... I guess OCaml is as close as it comes for the moment -- it's got everything I listed except a reasonable parallel execution story, but it looks like that's being worked on at the moment.