alejandra を Homebrew, Nix でインストール

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• alejandra

プロジェクトの歴史

The official README brands Alejandra as 'The Uncompromising Nix Code Formatter' and says it was written in Rust, formats Nixpkgs in seconds, and starts from the original Nixpkgs style refined by feedback from developers using Nix at scale.

The changelog shows a fast maturation arc in 2022. Version 1.0.0 shipped in March 2022; 1.4.0 and 1.5.0 followed with pre-commit support and dependency updates; 2.0.0 in July 2022 added a style guide, editor integration docs, and publication as a Rust crate with API docs; 3.0.0 in August 2022 simplified the CLI and improved large-file formatting order.

Later releases kept the formatter active in normal toolchain maintenance. Version 3.1.0 in 2024 refreshed integration docs and pre-commit hooks, and 4.0.0 in 2025 added experimental configurable indentation and support for newer Nix pipe operators.

採用の歴史

Alejandra's official README documents installation from Nixpkgs, Nix flakes, NixOS configurations, Homebrew, and prebuilt binaries. The supplied package facts also list Homebrew and Nix packages, which fits its primary audience: people already managing tools declaratively.

The README lists integrations for VS Code, Vim, Neovim, GNU Emacs, Doom Emacs, pre-commit, and pre-commit-hooks.nix. That adoption history matters because formatters become useful only when they are cheap to run in editors, CI, and repository hooks.

使われ方

Users run `alejandra` against Nix files, stdin, or repository trees, and often wire it into editor format-on-save or pre-commit hooks. The project treats the CLI, formatting rules, flags, exit codes, and stdout as its public API under semantic versioning.

Configuration is intentionally limited. The README documents an experimental `alejandra.toml` discovered in the current working directory, or supplied explicitly with `--experimental-config`.

パッケージ好きにとっての重要性

Alejandra is a package-nerd package because it formats the language used to describe packages in Nix. It is both a normal CLI package and a tool that shapes the readability of package expressions.

It also has the useful distribution trifecta for developer tools: Rust source, prebuilt binaries, and native Nix/Homebrew packaging, plus editor and hook integrations.

タイムライン

• 2022-03-03: Alejandra 1.0.0 released.
• 2022-05-19: Alejandra 1.4.0 added a pre-commit hook.
• 2022-07-13: Alejandra 2.0.0 added a style guide, editor integration docs, and crates.io publication.
• 2022-08-14: Alejandra 3.0.0 simplified the CLI and improved large-file formatting order.
• 2024-11-03: Alejandra 3.1.0 refreshed docs and pre-commit integration.
• 2025-04-10: Alejandra 4.0.0 added configurable indentation and Nix pipe-operator support.

Related projects

• The official README names NixEL, Santiago, and rnix-parser as related libraries.
• The README lists nixfmt, serokell/nixfmt, and nixpkgs-fmt as formatter alternatives in the same ecosystem.

ソース

• https://github.com/kamadorueda/alejandra/blob/main/CHANGELOG.md
• https://github.com/kamadorueda/alejandra/blob/main/README.md
• https://kamadorueda.com/alejandra
• source_facts.package-manager