feat(fmt): treefmt-nix support (#65)

- `nix fmt`
- `nix flake check`

.github/workflows/models.yml

@@ -41,13 +41,13 @@ jobs:
     steps:
       - name: Checkout repository
         uses: actions/checkout@v4
-        
+
       - name: Install Nix
         uses: DeterminateSystems/nix-installer-action@v9
 
       - name: Cache Nix artifacts
         uses: DeterminateSystems/magic-nix-cache-action@v2
-        
+
       - name: Test ${{ matrix.jl-file }}
         run: |
           nix develop -L . --command bash -c "julia -e 'using Pkg; Pkg.instantiate()'"

.github/workflows/update_flake_lock.yml

@@ -2,7 +2,7 @@ name: Update Flake Lock File
 on:
   workflow_dispatch: # allows manual triggering
   schedule:
-    - cron: '0 0 * * 0' # runs weekly on Sunday at 00:00
+    - cron: "0 0 * * 0" # runs weekly on Sunday at 00:00
 
 jobs:
   lockfile:
@@ -16,6 +16,6 @@ jobs:
         uses: DeterminateSystems/update-flake-lock@v20
         with:
           pr-title: "fix: update flake.lock" # Title of PR to be created
-          pr-labels: |                  # Labels to be set on the PR
+          pr-labels: | # Labels to be set on the PR
             dependencies
             automated

flake.nix

@@ -3,11 +3,13 @@
   inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
   inputs.flake-utils.url = "github:numtide/flake-utils";
   inputs.pre-commit-hooks.url = "github:cachix/pre-commit-hooks.nix";
+  inputs.treefmt-nix.url = "github:numtide/treefmt-nix";
 
-  outputs = { self, nixpkgs, flake-utils, pre-commit-hooks }:
+  outputs = { self, nixpkgs, flake-utils, pre-commit-hooks, treefmt-nix }:
     flake-utils.lib.eachDefaultSystem (system:
       let
         pkgs = nixpkgs.legacyPackages.${system};
+        treefmtEval = treefmt-nix.lib.evalModule pkgs ./treefmt.nix;
         tex = pkgs.texlive.combine {
           inherit (pkgs.texlive) scheme-small;
           inherit (pkgs.texlive) latexmk pgf pgfplots tikzsymbols biblatex beamer;
@@ -20,12 +22,21 @@
         julia = pkgs.julia-bin.overrideDerivation (oldAttrs: { doInstallCheck = false; });
 
       in
-      {
+      rec {
+        formatter = treefmtEval.config.build.wrapper;
+
         checks = {
+          formatting = treefmtEval.config.build.check self;
           pre-commit-check = pre-commit-hooks.lib.${system}.run {
             src = ./.;
             hooks = {
               typos.enable = true;
+              treefmt = {
+                enable = true;
+              };
+            };
+            settings = {
+              treefmt.package = treefmtEval.config.build.wrapper;
             };
           };
         };