Elixir could do with a decent tracer library that’s available out of box. With the greatest of respect for the original authors of erlang the semantics of the bundled :erlang tracers are not great, be it in terms of UX or overgreedy traces.
Redbug provides safety as it by-default terminates after a very conservative hit count (max time, max messages).
Unusually for an erlang module Redbug is self documenting on the erl repl.
I’m just using Redbug as an example, but it illustrates the sort of functionality that would be nice to have around.