elixir-development

Elixir Development

Production patterns for Elixir/OTP programming, covering Mix projects, GenServer, Supervisors, pattern matching, testing with ExUnit, and Phoenix basics.

When to Use This Skill

• Starting or structuring an Elixir project
• Building concurrent systems with OTP
• Implementing GenServers and Supervisors
• Writing pattern-matching-driven code
• Testing with ExUnit
• Working with Phoenix web framework
• Querying databases with Ecto

Core Concepts

1. Project Layout (Mix)

myapp/
├── lib/
│   ├── myapp/
│   │   ├── application.ex     # OTP Application (supervisor tree root)
│   │   ├── accounts/
│   │   │   ├── user.ex        # Ecto schema
│   │   │   └── accounts.ex    # Context module (business logic)
│   │   ├── workers/
│   │   │   └── email_worker.ex
│   │   └── repo.ex            # Ecto Repo
│   └── myapp.ex               # Public API
├── test/
│   ├── myapp/
│   │   └── accounts_test.exs
│   ├── support/
│   │   └── fixtures.ex
│   └── test_helper.exs
├── config/
│   ├── config.exs
│   ├── dev.exs
│   ├── test.exs
│   └── runtime.exs
├── mix.exs
├── mix.lock
└── README.md

2. Key Principles

Principle	Elixir Idiom
Immutability	All data is immutable; transform, don't mutate
Pattern matching	Destructure and branch in function heads
Pipe operator	Chain transformations with `
Let it crash	Supervisors restart failed processes automatically
Processes	Lightweight, isolated; communicate via messages

Quick Start

# Create a new project
mix new myapp --sup   # --sup includes Application supervisor

# Create a Phoenix project
mix phx.new myapp

# Get dependencies
mix deps.get

# Run tests
mix test
mix test --cover

# Interactive shell
iex -S mix

# Format code
mix format

Patterns