Ormolu vs Ruff

Ormolu is a formatter for Haskell source code. It uses GHC’s parser and applies one consistent style, with the aim of keeping diffs small. That style cannot be configured, and the project aims to leave code unchanged when it is formatted again after already meeting the style. Release binaries are available for Linux, macOS, and Windows; installation through cabal or stack is also supported. Ormolu Live provides a browser version. Listed editor integrations cover Emacs, VS Code, and Vim through neoformat or vim-ormolu, and Haskell Language Server has built-in support for Ormolu. For continuous integration, the project recommends the run-ormolu GitHub Action. It reads default language extensions and dependencies from a matching Cabal file;.ormolu files can specify fixity overrides and module re-export instructions. CPP support remains experimental and works only in simple cases where conditionals surround top-level declarations. Ormolu is open source and free, with a listed plan price of free.

Ruff is a Python linter and code formatter written in Rust, available free under a permissive open-source license. It includes more than 900 built-in lint rules, including native versions of popular Flake8 plugin rules, and can automatically correct violations such as unused imports. Its formatter aims to serve as a replacement for Black, though the documentation allows for differences in some cases. The built-in Ruff Language Server supplies diagnostics, fixes, and formatting; the documentation recommends pairing it with another Python language server for navigation and autocompletion. Setup guidance covers VS Code, Sublime Text, PyCharm, and Zed, while CI support includes GitHub Actions, GitLab CI/CD, and pre-commit hooks. Ruff can be installed through uv, pip, pipx, standalone installers, Homebrew, Conda, and other package managers. It supports configuration in pyproject.toml, ruff.toml, or .ruff.toml. A Bandit-derived rule group checks for common Python security issues. Ruff runs on Linux, macOS, and Windows, and is also published as a Docker image. The maker describes it as 10–100x faster than tools such as Flake8 and Black.