Overview

Understand the “why” behind Elixir patterns. Philosophy, idioms, and design principles.

What Are Explanation Documents?

Explanation documents provide:

• Conceptual Understanding: Why things work the way they do
• Design Philosophy: Principles behind Elixir’s design
• Best Practices: Industry-proven patterns with rationale
• Anti-Patterns: Common mistakes and why to avoid them

Unlike tutorials (how to do) or how-to guides (quick solutions), explanations help you think like an Elixir developer.

Available Resources

Best Practices

750+ lines covering what makes Elixir special:

“What Makes Elixir Special” Philosophy:

• Immutability and predictability
• Processes as isolation boundaries
• Supervision trees for fault tolerance
• Message passing over shared state
• “Let it crash” philosophy

Categories:

• Pattern Matching: When and how to use effectively
• Immutability: Benefits and patterns
• Processes: Right use cases for lightweight processes
• OTP: GenServer, Supervisor, Application patterns
• Phoenix: Web development idioms
• Testing: Test philosophy and organization

Each practice includes:

• Good Example: Idiomatic Elixir
• Bad Example: What to avoid
• Rationale: Why the good way is better
• When to Use: Appropriate contexts

Read Best Practices →

Anti-Patterns

750+ lines covering common mistakes:

For OOP Developers:

• Thinking in objects instead of processes
• Overusing GenServer for simple state
• Fighting immutability with workarounds
• Ignoring pattern matching power

Performance Anti-Patterns:

• Premature optimization
• Misusing processes
• Ignoring BEAM VM characteristics
• Over-engineering supervision trees

Testing Anti-Patterns:

• Over-mocking
• Testing implementation instead of behavior
• Ignoring property-based testing
• Complex test setups

Each anti-pattern includes:

• The Mistake: Code showing the anti-pattern
• Why It’s Bad: Consequences and problems
• Better Approach: The right way
• Migration Path: How to fix existing code

Study Anti-Patterns →

How to Use These Documents

For Understanding:

• Read after completing tutorials
• Understand design decisions, not just syntax
• Internalize Elixir philosophy

For Code Reviews:

• Reference best practices when reviewing
• Identify anti-patterns in existing code
• Share rationale with team

For Team Adoption:

• Establish shared understanding of “good” Elixir
• Create team-specific guidelines based on these principles
• Onboard new Elixir developers

Philosophy vs Practice

Best Practices (what to do):

• Concrete patterns
• Good/bad examples
• Actionable advice

Anti-Patterns (what to avoid):

• Common mistakes
• Why they’re problematic
• How to fix them

Together, they provide complete understanding of Elixir idioms.

Ready to understand Elixir deeply? Start with Best Practices →