# Elixir Coding Practices

> Use when authoring or reviewing Elixir, mix format, snake_case/CamelCase naming, module attribute order, pipelines, @moduledoc/@spec, Error exceptions, and mix test/credo in CI.

- Skill: `ryan-brosas/elixir-coding-practices` (Agent Skill)
- Install (CLI): `npx skillmds@latest add ryan-brosas/elixir-coding-practices`
- Raw SKILL.md: https://api.skillmd.com/api/skills/ryan-brosas/elixir-coding-practices/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: ryan-brosas (https://skillmd.com/u/ryan-brosas)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/ryan-brosas/elixir-coding-practices

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# Elixir Coding Practices

Application skill for Elixir style learning (from the archived `awesome-guidelines` style capsules). For OTP/supervision design, combine with stack capsules in `skills/*-foundation`.

## Core Principle

Elixir quality is **formatter-mechanical + explicit modules**, ordered attributes, documented public API, purposeful pipelines.

## When to Use / NOT

- Elixir/Phoenix/Mix libraries and applications.
- Setting up `mix format`, Credo, Dialyzer, ExUnit in CI.

**NOT when:**

- Erlang `.erl`, use Erlang practices when ingested.
- HEEx/templates only, validate `.ex` context modules.

## Workflow

1. **Format & modules**, mix format, module order (`elixir-style-formatting-modules.md`).
2. **Naming**, snake/Camel,?, Error (`elixir-style-naming-functions.md`).
3. **Expressions**, pipes, cond, defs (`elixir-style-expressions-pipelines.md`).
4. **Docs & types**, moduledoc, spec, errors (`elixir-style-docs-types-errors.md`).
5. **Verify**, `mix format`, `mix test`, Credo/Dialyzer per project.

## Red Flags

- Unformatted source
- camelCase functions or snake_case modules
- Single-step pipe
- `@moduledoc` after `use`
- Missing `@spec` on public API (when Dialyzer enabled)
- Exception not ending in `Error`
- Capitalized raise message with `.`
- `unless ... else`
- Repetitive module namespace (`Foo.Foo`)
- Needless macros

## Verification

- `mix format --check-formatted`
- `mix test`
- `mix credo` / `mix dialyzer` (project policy)
- ExDoc build for public packages
- Capsule checklist on new modules


## References

- `awesome-guidelines/references/elixir-style-learning-note.md`
- `awesome-guidelines/references/elixir-style-formatting-modules.md`
- `awesome-guidelines/references/elixir-style-naming-functions.md`
- `awesome-guidelines/references/elixir-style-expressions-pipelines.md`
- `awesome-guidelines/references/elixir-style-docs-types-errors.md`