I’m having so much fun working on the “Protohackers” challenges, I never got into Advent of Code much but this has been amazing. The challenges are all centered around protocols, so far they’ve all required you build a TCP server (gen_tcp makes it easy).

Also it’s an area Erlang/Elixir really excels at, so it’s fun to build lower level things that leverage all the great Erlang stuff, something I don’t think most of us get to do too often! Good opportunities to play with gen_tcp, messing with bits and bytes, and using binary pattern matching.

There’s an #elixir channel in the protohacker discord if you decide to jump in!

Couple last things to mention:

• ngrok doesn’t work, it seems to mess with TCP traffic, so I opened a port in my firewall and forwarded it to my laptop, then I provided that port along with my public IP. I liked that because I didn’t have to bother deploying my app to a VPS/Fly.io/etc. I just closed the port when I was done.
• The Elixir intro actually has a section where you implement an echo server with gen_tcp, it’s perfect for getting started.