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Elixir Flashcards (Basics)

Elixir Basics — Flashcards

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

Additional Flashcard Topics

  • Pattern Matching: case, withfunction heads. {:ok, value} = {:ok, 42} binds value to 42. Pin operator ^ matches existing values.

  • Pipe Operator: |> passes the result of the left side as the first argument to the right. Enables readable function chains: data |> parse() |> transform() |> save().

  • OTP GenServer: handle_call, handle_cast, handle_info. GenServer is a stateful process with a synchronous request/reply interface.

  • Supervision Trees: supervisors restart failed processes. Strategies: :one_for_one, :one_for_all, :rest_for_one. “Let it crash” philosophy.

  • Concurrency: processes are lightweight (not OS threads). Message passing with send/receive. Elixir processes are isolated, one crash doesn’t affect others.

  • Protocols and Behaviours: protocols provide polymorphism; behaviours define callback interfaces. Similar to type classes (Haskell) or traits (Rust).

Intuition

Elixir runs on the Erlang VM (BEAM), designed for building fault-tolerant, distributed systems. Everything is a function call, there are no loops, only recursion and higher-order functions like Enum.map. Pattern matching is pervasive: it’s used for function dispatch, error handling (case/with), and data destructuring. OTP provides battle-tested building blocks (GenServer, Supervisor) that implement the “let it crash” philosophy, processes fail independently and supervisors restart them. Elixir combines the robustness of Erlang with a modern, Ruby-like syntax.

Common Pitfalls

  • Pipe operator precedence: The |> pipe operator has low precedence, expressions in the pipe chain can bind unexpectedly. Use parentheses for complex arguments.
  • Agent vs GenServer: Using Agent for anything beyond simple state, Agent is a convenience wrapper; GenServer gives you full control over handle_call/handle_cast/handle_info.
  • Binary pattern matching: Forgetting that <<a, b::binary>> matches a byte and the rest as binary, b::binary is required to capture remaining bytes, not just b.
  • Tail recursion: Not all recursion is tail-recursive. Only the last call being the recursive call (with no further computation) allows the BEAM to optimise stack usage.
  • Erlang vs Elixir syntax: Elixir compiles to Erlang bytecode. Understanding Erlang documentation and error messages is essential for debugging.

Cross-References

Advanced Content

This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.

Derivations and Proofs

Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.

Extended Examples

Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.

Research Connections

This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.

Prerequisites

Ensure you have mastered the prerequisite material before attempting this advanced content.