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Elixir / Collections

Enum.reduce

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

10 min read • Beginner

Enum.reduce is a focused Elixir lesson inside Collections. The example uses the construct named in the lesson directly rather than reusing a generic placeholder.

Trace the example from its inputs through Enum.reduce 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-0023-1057b7fed2.exs
elixir Try It Live 
total = Enum.reduce([12, 5, 8], 0, fn n, acc -> n + acc end)
IO.puts(total)
Edge case / engineering note

For Enum.reduce, 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

Enum.reduce Mastery Check →
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