chore: add treefmt formatting (nix fmt + pre-commit + CI check)#4
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Wire treefmt via treefmt-nix: nixfmt, dhall format, purs-tidy (.tidyrc.json) and LuaFormatter for the FFI (.lua-format, kept over StyLua because it preserves the parentheses pslua's parser needs). `nix fmt` formats; the dev shell installs a content-based pre-commit hook and CI runs `nix fmt && git diff --exit-code` (content-based, since the in-place formatters bump mtime and would trip treefmt --fail-on-change). Lua lines budget 130 cols, matching the raised `luacheck --max-line-length`. The bulk of the diff is the first format pass.
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Pull request overview
Adds standardized, Nix-native formatting via treefmt across the repo (Nix/Dhall/PureScript/Lua), with local developer workflow integration and CI enforcement.
Changes:
- Introduces
treefmt.nixplus formatter configs for purs-tidy and LuaFormatter. - Wires treefmt-nix into the flake to provide
nix fmt, a formatting check derivation, and a devshell-installed pre-commit hook. - Updates CI, docs, and luacheck settings to enforce formatting/line-length consistently.
Reviewed changes
Copilot reviewed 6 out of 9 changed files in this pull request and generated 1 comment.
Show a summary per file
| File | Description |
|---|---|
treefmt.nix |
Defines treefmt formatters (nixfmt, dhall, purs-tidy, lua-format) and excludes generated/vendored paths. |
spago.dhall |
Dhall formatting cleanup (whitespace). |
flake.nix |
Adds treefmt-nix input, exposes formatter/checks.formatting, and installs a pre-commit hook via shellHook. |
flake.lock |
Pins treefmt-nix input. |
AGENTS.md |
Documents formatting workflow and updates luacheck max line length. |
.tidyrc.json |
Adds purs-tidy configuration. |
.lua-format |
Adds LuaFormatter configuration. |
.gitignore |
Un-ignores new formatter config dotfiles. |
.github/workflows/ci.yml |
Adds format-check step and aligns luacheck line length with config. |
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Roll the ecosystem formatting setup (ADR 0007, piloted in purescript-lua/purescript-lua-effect#6) onto this fork.
Tooling. Copies
treefmt.nix/.tidyrc.json/.lua-formatand wires treefmt-nix into the flake:nix fmtformats,checks.formattingis exposed, the dev shell installs a content-based pre-commit hook, and CI gains a format-check step. The check is content-based (nix fmt && git diff --exit-code) rather thantreefmt --ci, since the in-place formatters bump mtime even when content is unchanged. LuaFormatter is kept over StyLua because it preserves the parentheses pslua's foreign-file parser requires;luacheck --max-line-lengthraised to 130 to match.Diff. The bulk is the first
nix fmtpass over*.pursand the*.luaFFI. Verified locally: build +luacheck --max-line-length 130green.