Staff-Level Elixir

Distilled staff-level judgment for Elixir on the BEAM — the design decisions Elixir, OTP, Ecto, and Phoenix force, and how an experienced engineer settles them, written so an agent applies them while writing or reviewing code. Each rule corrects a specific wrong default; there is no rule for things the model already gets right (syntax, basic idioms, the standard library).

When to Apply

• Writing or reviewing OTP code — deciding whether something needs a process, and which (GenServer, Task, Agent, ETS, supervisor)
• Handling failure — choosing between tagged tuples, exceptions, with, and letting a process crash
• Writing Ecto — queries, associations, transactions, changesets, large result sets
• Building Phoenix controllers and LiveViews — context boundaries, socket state, mount lifecycle
• Running concurrent work — parallel fan-out, fire-and-forget tasks, handling untrusted input
• Any request to make Elixir code more idiomatic, more fault-tolerant, or "staff-level"

Rule Categories