The nine nines. 99.9999999% of uptime. Whether the AXD301 actually deserves to be held up as a system of nine nines seems debatable. I am not particularly interested in that debate. Erlang has a strong record for reliability and a design intended to help you as a developer and operator achieve your nines. Maybe just five of them. Up to you really.
Elixir was built on Erlang. Erlang was built to provide "consistently low latency" and a few other audacious goals. Note, this is not a hard realtime constraint. It is soft, squishy and yet, important and real. It makes Erlang unusually suitable to systems where latency matters and where a near-realtime experience is necessary.
I've been using Elm since about one year back now. At the start of 2021 I began working with a client that had an existing Elm frontend code base and an early stage backend built in Elixir and Phoenix. This post will be about my experiences running face first into Elm. I'll be vague on some details as I can't share too much about the specific client and code base. I'll be much less vague about Elm itself.