dprint vs Fourmolu

dprint is a command-line application that automatically formats code through a configurable, pluggable system built with Rust and WebAssembly. Its official and wrapper plugins cover languages and formats including TypeScript, JavaScript, JSON, Markdown, TOML, CSS, Dockerfile, C#, Python, Go, Swift, GraphQL, YAML, PHP, LaTeX, R, and Julia. Project configuration files define plugins, formatting settings, included files, and exclusions. Plugins can be loaded from a URL or file path and pinned or versioned in configuration. The project says dprint formats hundreds of files in milliseconds and enables incremental caching by default. WebAssembly plugins run in a sandbox without network or file-system access, while process plugins are executable files and are not sandboxed. Editor integrations are listed for Visual Studio Code, IntelliJ, and Neovim; the language-server command can also be used by other editors. The CLI is distributed as a static binary with no runtime dependencies, with installation options including shell, PowerShell, Cargo, npm, and Homebrew. It is MIT-licensed and free.

Fourmolu is a configurable formatter for Haskell source code and a fork of Ormolu. It uses GHC’s parser and aims to keep diffs small, produce idempotent output, and handle large projects. Set formatting options in `fourmolu.yaml` or pass them on the command line. Controls include indentation, line length, import grouping, record layout, Haddock comments, Unicode output, and operator fixities. Fourmolu can find the relevant Cabal file to read default extensions and dependencies that help determine fixities. Magic comments can disable formatting for selected code, and command-line options can target a line region. There is an interactive browser demo with configurable formatting and program options. Installation instructions cover GHCup, Cabal, Stack, and dotslash; editor integration is documented through Haskell Language Server. The project recommends a GitHub Action to keep projects formatted. Its listed current release is v0.21.0.0. CPP handling is experimental and limited to simple cases where conditionals surround top-level declarations. Output always uses LF line endings, which can cause check mode to fail on CRLF files.