Elixir Style: Prefer Unnested Aliases

This post was originally written for my old ElixirFocus blog, and transfer here after its closure.

In Elixir, alias is a keyword we often use to create shorthand references to long-form module names allowing us to refer to RetroTaxi.Boards.Board simply as Board.

You’ll often end up with a collection of alias declarations at the top of a module, and Elixir offers two ways to format these.

One way is simple list such as:

alias RetroTaxi.Boards.Board
alias RetroTaxi.Boards.Column
alias RetroTaxi.Boards.TopicCard

The other way is an optional nested list like:

alias RetroTaxi.Boards.{Board, Column, TopicCard}

Sometimes this nested list is broken across separate lines and presented like:

alias RetroTaxi.Boards.{
    Board, 
    Column, 
    TopicCard
}

Style Recommendation

I highly recommend avoiding this nested presentation. The primary reason is to help keep the codebase plain-text searchable. By avoiding the nesting, you can quickly find which modules are referencing any module simply by searching for its name string like RetroTaxi.Boards.Column. Finding nested aliases would require a more complex regular expression or language server tooling.

If you want to enforce this style with a credo, check out Credo.Check.Readability.MultiAlias which is usually disabled on a default credo install.