[masukomi]

biggest pro: elixir is built on erlang. Erlang was made to have incredible multithread performance distributing messages on computers from decades ago.

All those scaling problems Mastodon admins complain about? 99% of wouldn't exist if they were using one of the Phoenix based fediverse apps instead of the Rails based one (mastodon). Sure, some of the larger instances would still have issues but most folks would get plenty of throughput on one average machine.

Erlang's a great language. Once you wrap your head around the fact that = is a "match" operator and not an assignment operator... ;)

My day job is as a back-end rails dev, but I was introduced to Phoenix by a couple of the most prominent folks in that community. It is my belief that Elixir and Phoenix are unquestionably a better choice than Rails for new work. The only reasons to use Rails instead are that ruby has a bigger ecosystem of libraries, and none of your staff knows Elixir. Alternately that you're a ruby dev who's just whipping out something quick and performance doesn't, and won't, matter.