> With care you can attach a repl to a remote running program
That's good, but it's also table stakes. Drb (in the standard library) lets you remote access any Ruby object, so if you want a remote REPL, it's is simply a case of injecting a Drb server. Hence e.g. pry-remote which remotes the Pry REPL, but you can also then remote any already existing object in any running application.
I mean the equivalent is also possible out of the box Erlang VM. Without having to install sidecar servers or monkey patching objects with potentially spooky action at a distance.
Erlang, from day 1, was designed to be logged in to remotely. No other system is remotely close to the sophistication that Erlang (and as a result elixir) has in this regard
That's good, but it's also table stakes. Drb (in the standard library) lets you remote access any Ruby object, so if you want a remote REPL, it's is simply a case of injecting a Drb server. Hence e.g. pry-remote which remotes the Pry REPL, but you can also then remote any already existing object in any running application.