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Values and Matching
Integers floats and atoms Strings and charlists Tuples Lists Maps Keyword lists Pattern matching Pin operator Guard clauses Underscore ignored values
Functions and Pipelines
Anonymous functions Named functions Default arguments Multiple function clauses Private functions Pipe operator Capture operator Recursion Tail recursion Higher-order Enum functions
Collections
Enum.map Enum.filter Enum.reduce Enum.find Enum.group_by Stream.map laziness Range enumeration List comprehensions Map.update MapSet uniqueness
Modules and Structs
Modules Aliases Imports Requires Module attributes Structs Enforced keys Protocols Protocol implementations Behaviours
Errors and Control
If and unless Case Cond With Try rescue Catch and throw After cleanup Raise Custom exceptions Error tuples
Processes and Messages
Spawning processes Sending messages Receive blocks Process links Process monitors Task.async Task.await Agent state GenServer calls GenServer casts
OTP and Supervision
Supervisor child specs One-for-one strategy DynamicSupervisor Registry Application module Process naming Timeout handling Terminate callbacks ETS tables Persistent term
Files Data and Testing
File.read File.write Path operations Jason-style JSON modeling Regex Date and DateTime IO streams ExUnit tests Doctests Mix tasks
Elixir / Modules and Structs

Protocols

Learn Protocols in Elixir through a focused explanation, a dedicated topic-specific example, an engineering boundary, and a mastery check.

12 min read • Intermediate

Protocols is a focused Elixir lesson inside Modules and Structs. The example uses the construct named in the lesson directly rather than reusing a generic placeholder.

Trace the example from its inputs through Protocols and identify the behavior that would change if that construct were removed or replaced. Pay attention to the language-specific rules shown by the syntax, because neighboring lessons intentionally exercise different mechanisms.

Topic-specific example

elixir-0038-e96438f725.exs
elixir Try It Live 
values = [39, 40, 41]
IO.inspect(Enum.sum(values)) # Protocols
Edge case / engineering note

For Protocols, test one realistic boundary: empty data, invalid input, unavailable resources, lifetime/cleanup, type constraints, or concurrency timing where applicable. A successful happy path is not enough to prove the construct is used correctly.

Content source & attribution
Original Syntaxis Content · Original Syntaxis Content

Lesson quizzes

Protocols Mastery Check →
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Protocol implementations