Elixir is a nice functional language. Not as purely functional as Haskel mind.
It is based off of Erlang and runs on the Erlang VM. Syntax is Ruby inspired. It is not a high performant language (like C, Rust, etc), but it excels at distributed computing and fault tolerance. There is excellent documentation and tooling for it as well.
ultra.cc user here as well. Cheapest option (no streaming) and am super happy. Yes, it's not a dedicated connection but it is sufficiently fast. Shell access to the box, easy app installers, webdav, sftp, and web access. Egress over ssh (rsync/rclone) does not count towards bandwidth (unlike http(s)) Been using them for 6 months now.