The article author wrote this ESLint plugin to do just that https://github.com/jfmengels/eslint-plugin-fp https://github.com/jfmengels/eslint-plugin-fp then he

The article author wrote this ESLint plugin to do just that https://github.com/jfmengels/eslint-plugin-fp https://github.com/jfmengels/eslint-plugin-fp then he (I) happily switched to Elm, because even with a lot of static analysis rules, it's really hard to avoid impure functions when a lot of the libraries and existing code use that, and sometimes even require that.