Tools: 150k Lines Of Vibe Coded Elixir: The Good, The Bad And The Ugly

BoothIQ is a universal badge scanner for trade shows. AI writes 100% of our code. We have 150,000 lines of vibe coded Elixir running in production. Here’s what worked and what didn’t.

Elixir is a small language. Few operators. Small standard library. Only so many ways to control flow. It hasn’t been around for decades. It hasn’t piled up paradigms like .NET or Java, where functional and OOP fight for space.

This matters. AI is bad at decisions. If you want your agent to succeed, have it make fewer decisions. With Elixir, Claude doesn’t need to pick between OOP and functional. It doesn’t need to navigate old syntax next to new patterns. There’s one way to skin the cat. Claude finds it.

This matters more if you’re adding AI to an existing codebase. In languages where paradigms came and went—often with whatever developer pushed them—Claude tries to match the existing code. The existing code is inconsistent. So Claude is inconsistent.

Small and terse are related but different. Small means few concepts. Terse means fewer tokens to express the same thing. Go is small but not terse—few concepts, but verbose syntax and explicit error handling everywhere. Elixir is both. We got lucky.

Context windows are a real constraint. Elixir uses fewer tokens than most languages. No braces. No semicolons. No verbose boilerplate. I can stay in a working session longer. More iterations. Fewer compactions—those moments when the AI summarizes and forgets earlier context. More context in memory.

When I built the React Native version of our app, I hit compactions constantly. JavaScript is small-ish, but it’s not terse. It burns tokens to do what Elixir does with fewer.

I also see more compactions when working on heavy HTML and Tailwind in LiveView. Adding, updating, or editing large sections of markup at once. HTML and HEEx templates are token-heavy. But even then, it’s less painful than JavaScript-heavy work.

Tidewave supercharges Elixir-specific context. It lets the agent read logs from the running app—debug, info, error, warning—so you don’t copy/paste logs around. It can query the dev database, see Ecto schemas, and view package documentation. Fewer hallucinations. Longer unassisted runs. The agent can check and validate its own assumptions without human intervention.

If a variable gets mutated by a function call, AI now has three problems instead of one. The actual feature you want implemented. Whether to work around the mutation or update other call sites to stop muta

Source: HackerNews