Linters

Credo: linter as teacher

Linters are important because they automate tedious style and code quality checks. Linter rules don’t exist in a vacuum. The coding rules come from the language community. As the language evolves, so does the linter. One of the most useful libraries for code consistency is René Föhring’s Credo. It’s a linter like Ruby’s Rubocop or JSLint for JavaScript, but as it proclaims in the tagline on GitHub, it’s a linter “with a focus on code consistency and teaching.” That aim is what makes Credo so interesting.

With a standard linter, you might get some warning or suggestion, and instead of understanding the issue, you make the change and move on. The linter helps improve the quality of the code, but it doesn’t give the developer much context as to why these changes are necessary.

Credo, too, tells you “what”, but also answers “why”.

Let’s look at a contrived simple MixMix is a build tool that ships with Elixir that provides tasks for creating, compiling, testing your application, managing its dependencies, and much more. application.

Note: Mix is an Elixir executable. This means that in order to run mix, we need to have both mix and elixir executables in your PATH. That’s what happens when Elixir is installed.

Elixir has a package manager called Hex. Every time we add a dependency to the project, Hex is responsible for downloading it. Many packages in Hex are named after the package domain followed by an _ex prefix, such as html_sanitize_ex, kafka_ex, and many others.

Our application will “hexify” library names by appending _ex to the given string unless one already exists. We have already created the application for you, but if you want to make one locally, you can create it using the command: