Basics

This check is disabled by default.

Learn how to enable it via .credo.exs.

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

Explanation

@impl true is a shortform so you don't have to write the actual behaviour that is being implemented. This can make code harder to comprehend.

preferred

@impl MyBehaviour
def my_funcion() do
  # ...
end

NOT preferred

@impl true
def my_funcion() do
  # ...
end

When implementing behaviour callbacks, @impl true indicates that a function implements a callback, but a more explicit way is to use the actual behaviour being implemented, for example @impl MyBehaviour.

This not only improves readability, but adds extra validation in cases where multiple behaviours are implemented in a single module.

Like all Readability issues, this one is not a technical concern. But you can improve the odds of others reading and liking your code by making it easier to follow.

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.