Mastering Elixir in 2024: A study path

Most developers learn Elixir backwards. They install Phoenix, scaffold a project, marvel at LiveView, and then spend the next two years writing object-oriented code with a functional syntax. I know this because I almost did it myself.

The problem is not Phoenix. Phoenix is extraordinary. The problem is reaching for the framework before understanding the machine underneath it. Elixir is not Ruby with better concurrency. It is not “just another web language.” It is a fundamentally different way of thinking about systems — and that thinking is rooted in OTP and the BEAM virtual machine, which have been quietly running the world’s telecom infrastructure for over three decades.

This article is my study path for 2024. Not a generic “getting started” guide. Not a list of tutorials. This is the deliberate, phased plan I am following to move from proficient to something approaching mastery. Every phase has a reason. Every phase unlocks a specific capability. And the order matters more than most people think.

Phase 1: Rewire Your Brain — The Fundamentals

Timeline: 4-6 weeks What this unlocks: The ability to think in transformations instead of mutations

If you have spent most of your career in object-oriented languages — Java, PHP, Ruby, Python — the first phase is not about learning syntax. It is about unlearning habits. You need to stop thinking in terms of objects that hold state and methods that mutate it. Elixir demands that you think in terms of data flowing through transformations.

Three concepts will rewire your brain faster than anything else:

Pattern matching is the gateway. It is not just destructuring. It is a control flow mechanism, an assertion mechanism, and an argument dispatch mechanism rolled into one. When you write multiple function heads with different patterns, you are replacing entire blocks of conditional logic with something more declarative and more robust.

def process(%{status: :active, balance: balance}) when balance > 0 do
  # Only matches active accounts with positive balance
end

def process(%{status: :suspended} = account) do
  # Handles suspended accounts
end

def process(_account), do: {:error, :unhandled_state}

The pipe operator is where Elixir’s expressiveness crystallizes. Once you internalize |>, you stop writing nested function calls and start writing data pipelines. This is not syntactic sugar. It fundamentally changes how you decompose problems.

raw_input
|> String.trim()
|> String.split(",")
|> Enum.map(&String.to_integer/1)
|> Enum.filter(&(&1 > 0))
|> Enum.sum()

Recursion and immutability are the final pieces. There are no loops. There is no mutable state. This sounds restrictive until you realize it eliminates entire categories of bugs — race conditions, unexpected side effects, the kind of state corruption that makes you question your career choices at 2 AM.

What to Read

Start with Programming Elixir by Dave Thomas. Not because it is the newest or flashiest resource, but because Thomas does something rare: he teaches you to think in Elixir rather than translating from another language. Read it cover to cover. Do the exercises. Do not skip the chapters on pattern matching and recursion even if you think you understand them.

Supplement with the official Elixir Getting Started guide. It is one of the best language introductions ever written. Concise, well-structured, and maintained by people who actually use the language.

What to Build

Build a command-line tool. Something that takes input, transforms it, and produces output. A CSV parser. A Markdown-to-HTML converter. A simple calculator that handles arbitrary expressions. The constraint is important: no web framework, no database, no external dependencies beyond the standard library.

The goal is to force yourself to solve problems with pattern matching, recursion, and the Enum and Stream modules. If you reach for a library, you are skipping the lesson.

What to Skip

Skip LiveView demos. Skip Phoenix tutorials. Skip anything that starts with mix phx.new. You are not ready, and that is fine.

Phase 2: OTP — The Real Differentiator

Timeline: 6-8 weeks What this unlocks: The ability to build systems that self-heal

This is the phase most developers rush through or skip entirely. It is also the phase that separates people who use Elixir from people who understand it.

OTP is not a library. It is a philosophy of system design that happens to come with an incredibly powerful set of abstractions. The core insight is this: failure is not an edge case to be prevented. It is an expected condition to be managed. Your system will crash. OTP gives you the tools to make crashing a feature rather than a catastrophe.

GenServer is where you start. It is the workhorse abstraction — a process that maintains state, handles synchronous and asynchronous messages, and can be supervised. Most stateful components in an Elixir system are GenServers under the hood.

defmodule AccountCache do
  use GenServer

  def start_link(opts) do
    GenServer.start_link(__MODULE__, %{}, opts)
  end

  def get(pid, account_id) do
    GenServer.call(pid, {:get, account_id})
  end

  @impl true
  def handle_call({:get, account_id}, _from, state) do
    {:reply, Map.get(state, account_id), state}
  end
end

Supervisors are the mechanism that makes “let it crash” possible. A supervisor watches processes and restarts them according to a strategy when they fail. The strategies — :one_for_one, :one_for_all, :rest_for_one — encode different dependency relationships between processes. Understanding when to use each one is the difference between a system that recovers gracefully and one that enters a restart loop.

Application is the top-level container that ties it all together. Every Elixir project is an OTP application. Understanding this — really understanding it, not just generating the boilerplate — changes how you architect systems.

What to Read

Elixir in Action by Sasa Juric is the single best resource for OTP. Juric builds up from processes to GenServers to supervisors to full applications with the kind of methodical rigor that makes the concepts stick. If you read only two Elixir books in your life, this should be one of them.

Follow it with Designing Elixir Systems with OTP by James Edward Gray II and Bruce Tate. This book focuses on the design decisions — how to decompose a system into processes, where to draw supervision boundaries, how to think about the lifecycle of data. It is less about the API and more about the architecture.

What to Build

Build a worker pool from scratch. Not with a library — from scratch. A module that maintains a pool of worker processes, dispatches tasks to available workers, and handles worker crashes by spawning replacements. This single project will force you to internalize GenServer, Supervisor, and the message-passing model.

Then build something stateful: an in-memory key-value store with TTL-based expiration. Use a GenServer for the store, a separate process for the expiration sweep, and a supervisor to manage both. When your expiration process crashes, it should restart without losing the data in the store.

I built a circuit breaker implementation using GenStateMachine for exactly this reason — it forced me to think about state transitions, failure modes, and supervision in a way that reading alone never could.

What to Skip

Skip Ecto. Skip database interactions entirely. OTP is about processes and state management in memory. Mixing in database concerns at this stage muddies the learning.

Phase 3: The Ecosystem — Your Professional Toolkit

Timeline: 2-3 weeks What this unlocks: Production-grade code quality and workflow

This phase is shorter but critical. These are the tools that turn Elixir from a language you know into a language you can ship with.

Mix you have been using since Phase 1, but now go deeper. Understand how to write custom Mix tasks. Understand how mix.exs configurations cascade through environments. Understand how dependency resolution works. Understand releases with mix release.

Hex is the package manager. Learn to evaluate packages: check download counts, maintenance activity, and whether the library leans on NIFs or pure Elixir. A dependency that shells out to C is a different risk profile than one that does not.

ExUnit is the testing framework, and it is excellent. Learn property-based testing with StreamData. Learn how to test GenServers and supervised processes. Learn the difference between synchronous and asynchronous test assertions with assert_receive.

defmodule AccountCacheTest do
  use ExUnit.Case, async: true

  test "returns nil for missing keys" do
    {:ok, pid} = AccountCache.start_link([])
    assert AccountCache.get(pid, "nonexistent") == nil
  end
end

Credo enforces code consistency. It is not a linter in the traditional sense — it is more of a teaching tool that nudges you toward community conventions. Run it on every project. Pay attention to its suggestions about pipe chains, module structure, and naming.

Dialyzer (via Dialyxir) adds a type-checking layer to a dynamically typed language. It is slow the first time you run it. It will catch bugs that no amount of testing would. Use typespecs on your public functions and let Dialyzer verify them. This is not optional for production code.

What to Build

Take the projects from Phases 1 and 2 and retrofit them with full test suites, Credo compliance, Dialyzer typespecs, and proper Mix project structure. Write a custom Mix task that generates a report of your project’s health — test coverage, Credo score, Dialyzer warnings.

Phase 4: Phoenix and LiveView — Building for the Web

Timeline: 6-8 weeks What this unlocks: Full-stack web applications with real-time capabilities

Now you are ready for Phoenix. And because you spent time on OTP first, Phoenix will make sense in a way it never would have otherwise. You will see that a Phoenix channel is just a process. You will see that the endpoint is a supervision tree. You will see that Ecto repos are GenServers.

This is why the order matters.

Start with the fundamentals: routing, controllers, contexts, and templates. Phoenix’s context system is an opinionated way of organizing business logic, and it is a good opinion. Resist the urge to put logic in controllers. Controllers are thin dispatchers. Contexts are where the work happens.

Ecto deserves serious attention. It is not an ORM — the Phoenix team will correct you on this, and they are right. It is a data mapping and query composition toolkit. Learn changesets deeply. Learn how to compose queries with Ecto.Query. Learn multi-tenancy patterns and how to work with multiple repos.

def list_active_accounts(organization_id) do
  Account
  |> where([a], a.organization_id == ^organization_id)
  |> where([a], a.status == :active)
  |> order_by([a], desc: a.inserted_at)
  |> Repo.all()
end

LiveView is where Phoenix transcends the traditional request-response model. Real-time UI updates without writing JavaScript. But do not treat it as a magic trick. Understand what happens on the wire. Understand the lifecycle of a LiveView process. Understand when LiveView is the right tool and when a traditional controller action is simpler and better.

LiveView is right for: dashboards, forms with real-time validation, collaborative editing, anything where the user needs to see changes without refreshing. LiveView is wrong for: static content pages, SEO-critical landing pages, anything that does not need real-time updates. Use the right tool.

What to Read

The official Phoenix guides are genuinely good. Start there. For Ecto specifically, Programming Ecto by Darin Wilson and Eric Meadows-Jonsson is the definitive resource.

For LiveView, the official documentation has improved dramatically. Supplement it with Programming Phoenix LiveView by Bruce Tate and Sophie DeBenedetto.

What to Build

Build a project management tool. Not a toy — something with user authentication (use mix phx.gen.auth), real-time updates via LiveView, a PostgreSQL-backed data layer with Ecto, and proper context boundaries. This project exercises every major component of the Phoenix stack.

Then add a real-time dashboard that shows live metrics. Use PubSub to broadcast events from your contexts to LiveView processes. This is where OTP knowledge from Phase 2 pays off directly — you will naturally reach for GenServers to aggregate metrics and PubSub to distribute them.

Phase 5: The Deep End — Advanced Topics

Timeline: Ongoing What this unlocks: The ability to push the platform to its limits

This phase does not have a fixed endpoint. These are the topics you explore as specific problems demand them.

Metaprogramming is Elixir’s most powerful and most dangerous feature. Macros let you extend the language itself — Phoenix’s router, Ecto’s query syntax, and ExUnit’s test macro are all built with metaprogramming. Read Metaprogramming Elixir by Chris McCord before writing a single macro. The first rule of macros: do not write a macro if a function will do.

# This is a macro. Make sure you actually need one.
defmacro log_execution(func_call) do
  quote do
    start = System.monotonic_time()
    result = unquote(func_call)
    elapsed = System.monotonic_time() - start
    Logger.info("Executed in #{elapsed}ns")
    result
  end
end

NIFs (Native Implemented Functions) let you call C or Rust code from Elixir. This is how you solve the rare performance-critical hot path that the BEAM cannot handle alone. Rustler makes Rust NIFs safe and ergonomic. But a NIF that crashes takes down the entire VM, not just a process. Use them sparingly and with extreme caution.

Distributed Elixir is where the BEAM’s heritage in telecom really shines. Connecting nodes, distributed process registries with libraries like Horde, distributed state with CRDTs — these are the tools for building systems that span multiple machines. Start with libcluster for node discovery and work up from there.

Nerves deserves a mention for anyone interested in IoT. Running Elixir on embedded hardware sounds like a novelty until you realize that the fault-tolerance guarantees of OTP are exactly what you want in a device you cannot physically access to restart.

What to Build

Pick a problem that genuinely interests you and demands one of these advanced capabilities. A distributed task queue. A code analysis tool that uses macros to instrument modules. A hardware monitoring system with Nerves. The project should scare you slightly. That is how you know it is the right one.

The Counter-Argument: “Just Build Things”

I have heard the objection. “This is too structured. Just build projects and learn as you go.” There is truth in this — you cannot learn Elixir purely from books. But unstructured exploration has a cost. I have seen developers spend months building Phoenix apps without understanding supervision trees, and then hitting a wall the first time they need a background job that does not crash their entire application.

The “just build things” approach works for languages where the runtime is simple and the framework is the product. Ruby is Rails. PHP is Laravel. But Elixir is the BEAM. The framework is a thin layer over a runtime that has more to teach you than any web framework ever could.

Structure does not mean rigidity. Build things at every phase. But build the right things in the right order. Each phase gives you the mental model to make the next phase productive instead of confusing.

What Mastery Actually Looks Like

Mastery is not knowing every function in the standard library. It is not having memorized the OTP documentation. Mastery is a way of seeing.

When you look at a problem and instinctively decompose it into processes with clear boundaries and failure domains — that is mastery. When you design a supervision tree on a whiteboard before writing a line of code — that is mastery. When you know that a GenServer is the wrong abstraction and an Agent or a Task is sufficient — that is mastery.

I am not there yet. This study path is my map for getting closer. The terrain is well-charted — Elixir has some of the best technical books and documentation of any modern language. The community, while smaller than Python’s or JavaScript’s, is disproportionately experienced and generous with knowledge.

The BEAM has been running production systems since 1986. Elixir gave it a modern interface. The opportunity in 2024 is not to learn a trendy language. It is to learn a battle-tested runtime through a language that makes it accessible.

That is worth doing deliberately.

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Recommended Reading List (in order):

1. Programming Elixir — Dave Thomas
2. Elixir in Action — Sasa Juric
3. Designing Elixir Systems with OTP — James Edward Gray II & Bruce Tate
4. Programming Ecto — Darin Wilson & Eric Meadows-Jonsson
5. Programming Phoenix LiveView — Bruce Tate & Sophie DeBenedetto
6. Metaprogramming Elixir — Chris McCord

Key Tools:

• Mix — Build tool and task runner
• Hex — Package manager
• ExUnit — Testing framework
• Credo — Static code analysis
• Dialyxir — Type checking via Dialyzer
• StreamData — Property-based testing