Elixir / OTP Project Rules

elixirotpbackend

Enforces Elixir and OTP conventions including GenServer patterns, supervision trees, pattern matching, pipeline style, and fault-tolerant process design.

Целевые файлы

Файл	Формат
.cursorrules	plaintext
CLAUDE.md	markdown

Содержимое

## Elixir / OTP Project Rules ### Project Structure - Follow the standard Mix project layout: `lib/[app]/`, `test/`, `config/` - Group related modules under a namespace: `MyApp.Accounts`, `MyApp.Billing` - Context modules (`Accounts`, `Billing`) are the public boundary — do not call internal modules from outside - Put OTP process modules (GenServers, Supervisors) in `lib/[app]/` with descriptive names - Configuration belongs in `config/config.exs`, `config/dev.exs`, `config/prod.exs` ### Pattern Matching - Use pattern matching in function heads as the primary dispatch mechanism - Match on the shape of data — not on `is_map`, `is_list` checks when pattern matching suffices - Use `=` for asserting structure in test setup and process messages - Handle all expected message shapes in `GenServer.handle_call/handle_cast/handle_info` - Use `_` to explicitly ignore values; never ignore values silently in assignment ### Pipe Operator - Use `|>` to express sequential data transformations — each step should be a named function - The first value in a pipe should be the subject; functions should take the subject as the first argument - Do not pipe into anonymous functions — extract to named private functions - Break long pipelines across lines, one pipe per line ### Functions & Modules - Public functions are documented with `@doc` and typed with `@spec` - Private functions use `defp`; only export what is part of the module's contract - Guard clauses go in function heads: `def process(x) when is_integer(x) and x > 0 do` - Keep functions short (under 20 lines); split long functions into private helpers - Use `with` expressions for multi-step operations that can fail at any step ### GenServer - Define `start_link/1` that accepts an options keyword list and calls `GenServer.start_link/3` - Define a client API (public functions) and server callbacks in the same module - Use `:via` tuple registration with `Registry` for named processes in a cluster - Never perform blocking I/O in `handle_call` — offload to `Task` and use `handle_cast` or `handle_info` - Handle unexpected messages in `handle_info` — log a warning and return `{:noreply, state}` ### Supervision Trees - Every OTP process must be started under a Supervisor — never use bare `spawn` - Use `:one_for_one` strategy for independent workers; `:rest_for_one` for ordered dependencies - Use `DynamicSupervisor` for processes created at runtime (e.g., per-user sessions) - Crash fast and let supervisors restart — do not catch errors that should be fatal to the process ### Error Handling - Use `{:ok, result}` and `{:error, reason}` tuples as the standard return convention - Use `with {:ok, x} <- step1(), {:ok, y} <- step2(x)` for chaining fallible operations - The `else` clause in `with` handles non-matching patterns — always include it for error translation - Let the process crash for unexpected errors — do not rescue `RuntimeError` in GenServers ### Ecto (Database) - Use `Ecto.Changeset` for all data validation and transformation — never mutate struct fields directly - Validate in changesets: `validate_required`, `validate_length`, `validate_format`, `unique_constraint` - Define queries as composable functions in a schema or query module: `User.active_query()` - Use `Repo.transaction(fn -> ... end)` for atomic multi-step operations - Use `preload:` in queries or `Repo.preload/2` — never access unloaded associations ### Concurrency - Use `Task.async` / `Task.await` for parallel work with a result - Use `Task.start` for fire-and-forget work that must not block the caller - Use `Task.async_stream` for parallel processing of collections with back-pressure - Always set a timeout on `Task.await` — default `:infinity` can hang processes ### Anti-patterns - Do not use process dictionary (`Process.put/get`) for passing state — it breaks transparency - Do not use `send`/`receive` directly — use GenServer APIs or PubSub - Do not write nested `case` expressions — use `with` or extract to functions - Do not ignore `{:error, reason}` return values — always handle or propagate errors

CLI

npx mindaxis apply elixir-rules --target cursor --scope project

Используется в паках

Не используется ни в одном паке

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