Fantomas vs rustfmt

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.

rustfmt formats Rust code according to style guidelines. It can format files directly or read code from standard input and write formatted output to standard output. With Cargo, `cargo fmt` formats binary and library targets in a crate and works with workspaces. A `rustfmt.toml` or `.rustfmt.toml` file can hold configuration, including stable and nightly-only options. For automated checks, `--check` returns code 0 when no formatting changes are needed and code 1 when changes would be made; it can be used in CI to fail a build on formatting differences. The README lists editor use with Vim, Emacs, Sublime Text 3, Atom, Visual Studio Code, IntelliJ, and CLion. Rustfmt is available on Windows, macOS, and Linux, and is distributed under the MIT License and Apache License 2.0. It does not attempt to format comments, and listed limitations also involve macros, unparsable code, fragments, and non-ASCII Unicode. Unstable settings require opt-in on nightly, and the README says the latest version requires the nightly toolchain.