Basics

This check has a base priority of normal and works with any version of Elixir.

Explanation

Encourages multi-line collections assigned to module attributes to list one item per line, so the collection stays easy to scan, diff, and update.

Once a list / word sigil / map / tuple assigned to a @module_attribute is broken across multiple lines, cramming several items onto one line makes it hard to see what changed in a diff and easy to mis-edit. Putting each item on its own line keeps every addition or removal to a single line.

Only module-attribute values are inspected, and only when the collection already spans more than one line. A single-line collection is always fine, no matter how many items it holds.

Covered forms: word sigils (~w[...] / ~W[...]), list literals ([...], including keyword lists), maps and structs (%{...} / %Mod{...}), and tuples ({...}). Interpolated ~w sigils are not inspected.

Bad — multi-line with more than one item on a line

@allowed_extensions ~w[
  .png .jpg .jpeg
  .gif .webp
]

@supported_locales [
  "en-US", "en-GB",
  "fr-FR", "de-DE"
]

@retry_backoff {
  1_000, 2_000,
  5_000
}

Good — one item per line

@allowed_extensions ~w[
  .png
  .jpg
  .jpeg
  .gif
  .webp
]

@supported_locales [
  "en-US",
  "en-GB",
  "fr-FR",
  "de-DE"
]

Good — a single line is fine, however many items

@allowed_extensions ~w[.png .jpg .jpeg .gif .webp]
@supported_locales ["en-US", "en-GB", "fr-FR", "de-DE"]

Check-Specific Parameters

There are no specific parameters for this check.

General Parameters

Like with all checks, general params can be applied.

Parameters can be configured via the .credo.exs config file.