Fantomas vs Ruff

Fantomas formats F# source code according to configuration, using default rules based on Microsoft’s F# style guide. Settings are also available for G-Research conventions. It runs as a .NET tool, and local installation is recommended when a repository needs to keep a fixed version. The command line accepts folders or files with `.fs`, `.fsi`, `.fsx`, `.ml` or `.mli` extensions; source files are expected to parse with the F# compiler before formatting. A limited selection of options can be placed in `.editorconfig` for automatic use by the command-line tool. For continuous integration checks, `dotnet fantomas check` reports formatting drift and exits with a failure code when files need formatting. Setup guides are available for JetBrains Rider, Visual Studio Code and Visual Studio, and the official site links to an online tool for trying the formatter and its settings. Fantomas and its library are available under the Apache 2.0 license. The project is described as an fsprojects incubation project. It is free and open source, with web access listed alongside Linux, macOS and Windows.

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.