Elixir Credo Error Fix

The Hook

You will learn how to fix common credo errors. This matters because understanding this concept is essential for productive development. Built by the developers of Doda Browser, DodaZIP, and Durga Antivirus Pro.

Quick Fix

Credo setup

The wrong approach and the correct fix are shown below:

Wrong:

# mix.exs
deps: [{:credo, "~> 1.6"}]

Output:

Right:

# mix.exs
defp deps do
  [{:credo, "~> 1.7", only: [:dev, :test], runtime: false}]
end
# Run: mix credo
# Config: .credo.exs
mix credo --strict
mix credo suggest # show suggestions only

Output:

Prevention

Credo is a static analysis tool. Checks consistency, readability, design.

Common Mistakes with credo

1. Overlapping type class instances that cause GHC to reject the program with ambiguous dispatch errors
2. Non-exhaustive pattern matches that compile with warnings then crash at runtime
3. Misunderstanding that String is [Char] with poor performance for large text operations

These mistakes appear frequently in real-world ELIXIR code. DodaTech's contributors have identified these patterns through analysis of open-source projects and production systems.

Practice Exercise

Write a pure function that safely divides two integers using Maybe, then test it with edge cases like division by zero and negative numbers.

This exercise reinforces the concepts covered in this guide. Try implementing it before checking online solutions.

FAQ