Quickstart

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Make Claude Code write production-ready Elixir, automatically.

This guide gets you from zero to format-checking, error-detecting Elixir code quickly.

What You'll Build

In this quickstart, you'll:

  1. Watch Claude Code detect formatting issues in code with long lines
  2. See compilation errors caught in real-time
  3. Experience the productivity boost firsthand

Prerequisites

  • Elixir 1.18+ installed
  • Claude Code CLI installed (install guide)
  • An Elixir project

Step 1: Install Claude

Run this single command:

mix igniter.install claude

When prompted:

  • Press Y to install Igniter (if not already installed)
  • Press Y to apply all changes

This automatically:

  • ✅ Adds Claude to your dependencies
  • ✅ Creates .claude.exs configuration
  • ✅ Installs formatting and compilation hooks
  • ✅ Sets up .claude/ directory structure
  • ✅ Installs bundled slash commands in .claude/commands/
  • ✅ Syncs usage rules from dependencies to CLAUDE.md

Step 2: Test Format Checking

Ask Claude Code to create a file with long lines:

Please create a file called lib/user_service.ex with this exact content:

defmodule UserService do
  def format_user_info(user) do
    "User: #{user.first_name} #{user.last_name} (#{user.email}) - Role: #{user.role}, Department: #{user.department}, Status: #{user.status}"
  end

  def build_response(user, account, preferences) do
    {:ok, %{user_id: user.id, account_id: account.id, name: user.name, email: user.email, preferences: preferences, created_at: user.created_at, updated_at: user.updated_at}}
  end
end

Watch the feedback! Claude will create the file, and immediately:

  • 🎨 Format checking runs
  • ⚠️ Claude is alerted that the file needs formatting (lines too long)
  • 🔧 Claude can run mix format to fix it

Step 3: Experience Compilation Checking

Ask Claude Code to introduce a warning:

Please edit lib/user_service.ex and rename the 'preferences' parameter to '_preferences'
in the build_response function (but still use 'preferences' in the function body)

Watch what happens:

  • ⚠️ Compilation warning detected immediately
  • 🔍 Warning details shown to Claude
  • 🔧 Claude can fix it automatically

Step 4: Try Pre-Commit Protection

Ask Claude Code to commit code with issues:

Please commit all changes with a descriptive message

If there are any formatting issues, compilation errors, or unused dependencies, Claude will:

  • 🛑 Block the commit
  • 📋 Show what needs fixing
  • 🔄 Help resolve issues before committing

Step 5: Try Slash Commands

Claude comes with bundled slash commands for common tasks. Type / in Claude Code to see all available commands, or try:

/mix:deps-check

This will check your dependency status using the bundled command. Other useful commands include:

  • /claude:status - Check Claude installation status
  • /mix:deps-add - Add new dependencies
  • /memory:nested-add - Configure nested memories for directories

What Just Happened?

You've just experienced Claude's core features:

  1. Format Checking - Every .ex and .exs file is checked for proper formatting
  2. Instant Compilation Checks - Warnings and errors caught immediately
  3. Pre-Commit Validation - Only clean code gets committed
  4. Intelligent Feedback - Claude sees and can fix issues automatically
  5. Bundled Commands - Pre-configured slash commands for common tasks
  6. Best Practices - Claude follows usage rules from your dependencies (see Usage Rules Guide)

Next Steps

Enable More Features

Troubleshooting

Claude hooks not running?

  • Run claude --version to verify Claude Code CLI is installed
  • Check .claude/settings.json exists
  • Try mix claude.install to reinstall hooks

Need help?

Learn More

🎉 Congratulations! You're now using Claude to write better Elixir code, automatically.