Configuration

pedantix is configured with a TOML file (see config discovery).

Individual values can also be passed on the command line with --set, e.g. pedantix --set lets.sort=true file.nix, or the whole document inline with --config-toml.

`preset`

This applies a base layer of configuration which you can layer your own config atop of - see Presets.

preset = "nixos-module"

Reference

Top-level keys

Key	Type	Default	Description
`format-after-sort`	bool	`true`	Run the base formatter again after sorting.
`format-before-sort`	bool	`true`	Run the base formatter before sorting.
`formatter`	`FormatterChoice`	`"nixfmt"`	Base formatter run before and after sorting.
`formatter-command`	list of string	—	Arbitrary `stdin -> stdout` command; overrides `formatter`. Because it runs an external program, it is only honored from configs named explicitly (`--config`, `--config-toml`, `--set`, the global XDG config); an auto-discovered config requires `--allow-formatter-command`.
`inherit-placement`	`InheritPlacement`	`"front"`	Where `inherit` statements land relative to ordinary bindings.
`top-level-blank-lines`	int	—	Exact number of blank lines between the bindings of the file's outermost attribute set. Unset keeps existing blank lines as-is.
`top-level-blank-lines-depth`	int	`1`	How deep the top-level spacing reaches: 1 is only the outermost set, 2 also covers the sets its bindings define, and so on. In `flake.nix`, `inputs` and `outputs` always count as top-level sets.
`top-level-blank-lines-mode`	`BlankLinesMode`	`"multiline"`	Which top-level bindings receive the blank-line spacing.

Construct rules (`[args]`, `[attrs]`, `[lets]`, `[inherits]`, `[lists]`)

The merge, flatten, and blank-lines* keys only apply to [attrs].

Key	Type	Default	Description
`blank-lines`	int	—	(attrs only) Number of blank lines between the set's bindings. Unset keeps the existing spacing.
`blank-lines-depth`	int	`1`	(attrs only) How deep the spacing reaches; wrappers such as functions and `let`s do not count as levels.
`blank-lines-mode`	`BlankLinesMode`	—	(attrs only) Which bindings receive the blank-line spacing.
`first`	list of string	`[]`	Names pinned to the front, in the given order. The sentinel `"<defaulted>"` stands for all arguments with a default value (`name ? value`); `"..."` is the ellipsis.
`flatten`	bool	`false`	(attrs only) Flatten a binding whose value is an attrset holding a single binding into one attrpath: `a = { b = 1; };` becomes `a.b = 1;`. Overrides match the path of the set being flattened.
`last`	list of string	`[]`	Names pinned to the end, in the given order.
`merge`	bool	`false`	(attrs only) Merge bindings sharing their first attrpath component into one nested set: `a.b = 1; a.c = 2;` becomes `a = { b = 1; c = 2; };`.
`sort`	bool	`true`	Whether to reorder this construct at all.

Override keys (`[[overrides]]`)

Key	Type	Default	Description
`args`	partial rules	—	Function-argument rules to apply to matched paths.
`attrs`	partial rules	—	Attribute-set rules to apply to matched paths.
`inherits`	partial rules	—	`inherit` rules to apply to matched paths.
`lets`	partial rules	—	`let`-binding rules to apply to matched paths.
`lists`	partial rules	—	List-element rules to apply to matched paths.
`path`	string	—	Glob over dot-separated attribute paths. `` matches exactly one component, `*` any number (including zero).

`FormatterChoice` values

Value	Description
`"nixfmt"`
`"alejandra"`
`"nixpkgs-fmt"`
`"off"`	Disable the base formatter; only reorder.

`BlankLinesMode` values

Value	Description
`"multiline"`	Space bindings whose text spans several lines; keep consecutive single-line bindings together.
`"all"`	Apply spacing to all bindings.
`"off"`	Suppress spacing entirely.

`InheritPlacement` values

Value	Description
`"front"`	Pin `inherit lines to the top of the set.
`"last"`	Pin `inherit lines to the bottom of the set.
`"sorted"`	Sort `inherit lines alphabetically among the bindings.

[args], [attrs], [lets], [inherits], and [lists] all take the same sort rules keys. Names not listed in first / last are sorted alphabetically between them. The merge, flatten, and blank-lines* keys are only meaningful under [attrs].

[args]
first = ["self", "lib", "config", "pkgs"]
last  = ["<defaulted>", "..."]

[attrs]
first = ["imports", "enable", "package"]

[lets]
sort = true

[lets], [inherits], and [lists] are off by default. List sorting in particular is best enabled per-path via an override rather than globally, since list order is often significant.

`merge` shared attribute paths

[attrs]
merge = true

turns a.b = 1; a.c = 2; into a = { b = 1; c = 2; };. This does not fix broken evaluation by e.g. dynamically derived attribute set names.

`flatten` single-binding attribute sets

[attrs]
flatten = true

turns a = { b = 1; }; into a.b = 1;, provided b is the only binding in the set. This skips on rec, inherit, dynamic keys, and comments around binding.

Top-level blank lines vs. `[attrs] blank-lines`

The top-level-blank-lines* keys and the [attrs] blank-lines* keys look similar but do slightly different things:

top-level-blank-lines does not descend into function-call sets, and treats a flake.nix inputs/outputs body as its own top-level set.

[attrs] blank-lines applies to every attrset the [attrs] rules match, at any nesting depth (including sets inside function calls), and can be targeted per path via [[overrides]].

A reordered set by default drops all blank lines, so set one of these to restore spacing.

`[inherits]` vs. `inherit-placement`

[inherits] sorts the names inside an inherit. The top-level inherit-placement key is separate: it controls where the whole inherit statement sits relative to other bindings.

Per-path overrides

The [[overrides]] array lets you change any of the rules above for specific attribute paths — see Overrides.