Elixir Flashcards (Basics) - Wyatt's Notes

Elixir Basics — Flashcards

20 flashcards covering core Elixir concepts. Tap a card to reveal the answer.

Intuition

Elixir is a functional language built on the Erlang VM (BEAM), designed for concurrency and fault tolerance. Pattern matching is its Swiss army knife — you destructure data and control flow in one expression. Think of processes as lightweight actors: millions can run concurrently, communicating via message passing. OTP provides battle-tested patterns like GenServer for building resilient applications that can recover from crashes automatically.

Common Pitfalls

• Mutable thinking: Trying to update a variable in place — Elixir variables are immutable bindings; use = pattern matching to bind new values, not reassign.
• Ignoring return values: Elixir functions always return the last expression — forgetting this leads to unexpected return values when refactoring.
• String vs charlist confusion: "hello" is a binary (UTF-8 encoded), while 'hello' is a charlist (Erlang-compatible list of codepoints) — mixing them up causes unexpected behaviour with string functions.
• Blocking in process message loops: Using receive without a timeout or catch-all clause can cause a process to hang indefinitely — always include a timeout or default handler in message loops.
• Supervision tree mistakes: Placing a frequently crashing worker directly under the root supervisor instead of behind a one_for_one strategy — this can cascade failures to unrelated services.

Study Tips

• Use IEx extensively: Elixir’s interactive shell (IEx) is excellent for experimenting with pattern matching, pipe operators, and OTP concepts. Run iex -S mix in your project to test functions in context.
• Trace GenServer calls: Use :sys.trace/2 or :observer to inspect GenServer state and message flow during debugging. Understanding message passing is key to building fault-tolerant applications.
• Start with mix new: Use mix new to scaffold projects with proper structure, test configuration, and dependency management from the beginning.
• Read the Elixir getting started guide: The official guide (elixir-lang.org/getting-started) covers fundamentals through advanced topics with clear examples. Work through each section sequentially.
• Build a Phoenix project: Phoenix is the standard Elixir web framework. Building a small Phoenix app demonstrates how Elixir’s concurrency model, supervision trees, and functional patterns work in practice.
• Practise pattern matching extensively: Pattern matching is Elixir’s most powerful feature. Write functions that destructure tuples, lists, and maps in a single expression.
• Study OTP GenServer: GenServer is the building block of concurrent Elixir applications. Understanding its callback model (init, handle_call, handle_cast, handle_info) is essential for building stateful services.
• Practise with the pipe operator: The |> operator chains function calls left-to-right. Rewrite nested function calls using pipes to make code more readable.

Cross-References

• Site Home: Main landing page for elixir notes.
• Practice: Practice problems for revision.

Detailed Content

This topic covers the fundamental principles and applications in depth. Each concept is explained with clear definitions, worked examples, and practice problems to reinforce understanding.

Core Concepts

Understanding these core concepts is essential for mastering this topic. They form the foundation for more advanced study and are frequently examined.

Worked Examples

Worked examples demonstrate how to apply the concepts to solve problems. Each example is broken down into clear steps with explanations.

Common Mistakes

• Rushing through foundational material
• Not practising problems after reading
• Failing to connect concepts across topics

Further Reading

Consult the recommended textbooks and additional resources for deeper understanding of this topic.

Detailed Content

This topic covers the fundamental principles and applications in depth. Each concept is explained with clear definitions, worked examples, and practice problems to reinforce understanding.

Core Concepts

Understanding these core concepts is essential for mastering this topic. They form the foundation for more advanced study and are frequently examined.

Worked Examples

Worked examples demonstrate how to apply the concepts to solve problems. Each example is broken down into clear steps with explanations.

Common Mistakes

• Rushing through foundational material
• Not practising problems after reading
• Failing to connect concepts across topics

Further Reading

Consult the recommended textbooks and additional resources for deeper understanding of this topic.

Detailed Content

This topic covers the fundamental principles and applications in depth. Each concept is explained with clear definitions, worked examples, and practice problems to reinforce understanding.

Core Concepts

Understanding these core concepts is essential for mastering this topic. They form the foundation for more advanced study and are frequently examined.

Worked Examples

Worked examples demonstrate how to apply the concepts to solve problems. Each example is broken down into clear steps with explanations.

Common Mistakes

• Rushing through foundational material
• Not practising problems after reading
• Failing to connect concepts across topics

Further Reading

Consult the recommended textbooks and additional resources for deeper understanding of this topic.

Detailed Content

This topic covers the fundamental principles and applications in depth. Each concept is explained with clear definitions, worked examples, and practice problems to reinforce understanding.

Core Concepts

Understanding these core concepts is essential for mastering this topic. They form the foundation for more advanced study and are frequently examined.

Worked Examples

Worked examples demonstrate how to apply the concepts to solve problems. Each example is broken down into clear steps with explanations.

Common Mistakes

• Rushing through foundational material
• Not practising problems after reading
• Failing to connect concepts across topics

Further Reading

Consult the recommended textbooks and additional resources for deeper understanding of this topic.

Detailed Content

This topic covers the fundamental principles and applications in depth. Each concept is explained with clear definitions, worked examples, and practice problems to reinforce understanding.

Core Concepts

Understanding these core concepts is essential for mastering this topic. They form the foundation for more advanced study and are frequently examined.

Worked Examples

Worked examples demonstrate how to apply the concepts to solve problems. Each example is broken down into clear steps with explanations.

Common Mistakes

• Rushing through foundational material
• Not practising problems after reading
• Failing to connect concepts across topics

Further Reading

Consult the recommended textbooks and additional resources for deeper understanding of this topic.