[bartblast]

It depends on what you're doing. I've been in Elixir web dev for about 7 years and never really needed to write or understand Erlang, outside of my work on Hologram. That said, Erlang is always there under the surface - it "leaks" into Elixir in places if you look at the stdlib, and understanding it gives you a better mental model of the whole platform. I'd say you don't need it on a daily basis for most Elixir work, but the runtime and OTP are incredible pieces of engineering, and getting to know Erlang better will only make you stronger in this ecosystem.

[atonse]

Just wanted to echo that my experience is almost identical (production elixir/phoenix for 10 years), and also very rarely touch erlang. But it does leak in every now and then.

And it'll feel less intimidating once you code in elixir, but I still find it more cryptic and less approachable the 3-4 times I've had to splunk into erlang to debug something in the last decade.