feat: add treefmt

flake.lock

@@ -125,7 +125,8 @@
         "fenix": "fenix",
         "flake-compat": "flake-compat",
         "flake-parts": "flake-parts",
-        "nixpkgs": "nixpkgs"
+        "nixpkgs": "nixpkgs",
+        "treefmt-nix": "treefmt-nix"
       }
     },
     "rust-analyzer-src": {
@@ -144,6 +145,26 @@
         "repo": "rust-analyzer",
         "type": "github"
       }
+    },
+    "treefmt-nix": {
+      "inputs": {
+        "nixpkgs": [
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1760120816,
+        "narHash": "sha256-gq9rdocpmRZCwLS5vsHozwB6b5nrOBDNc2kkEaTXHfg=",
+        "owner": "numtide",
+        "repo": "treefmt-nix",
+        "rev": "761ae7aff00907b607125b2f57338b74177697ed",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "treefmt-nix",
+        "type": "github"
+      }
     }
   },
   "root": "root",

flake.nix

@@ -19,6 +19,11 @@
       flake = false;
     };
 
+    treefmt-nix = {
+      url = "github:numtide/treefmt-nix";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+
     # for default.nix
     flake-compat = {
       url = "github:edolstra/flake-compat?ref=master";

nix/default.nix

@@ -6,5 +6,6 @@
     ./tests
 
     ./hydra.nix
+    ./fmt.nix
   ];
 }

nix/fmt.nix

@@ -0,0 +1,37 @@
+{ inputs, ... }:
+{
+  # load the flake module from upstream
+  imports = [ inputs.treefmt-nix.flakeModule ];
+
+  perSystem =
+    { self', lib, ... }:
+    {
+      treefmt = {
+        # repo root as project root
+        projectRoot = inputs.self;
+
+        # the formatters
+        programs = {
+          nixfmt.enable = true;
+          typos = {
+            enable = true;
+            configFile = "${inputs.self}/.typos.toml";
+          };
+          taplo = {
+            enable = true;
+            settings = lib.importTOML "${inputs.self}/taplo.toml";
+          };
+        };
+
+        settings.formatter.rustfmt = {
+          command = "${lib.getExe' self'.packages.dev-toolchain "rustfmt"}";
+          includes = [ "**/*.rs" ];
+          options = [
+            "--unstable-features"
+            "--edition=2024"
+            "--config-path=${inputs.self}/rustfmt.toml"
+          ];
+        };
+      };
+    };
+}

taplo.toml

@@ -0,0 +1,6 @@
+[formatting]
+align_entries = true # Align entries vertically. Entries that have table headers, comments, or blank lines between them are not aligned.
+
+reorder_arrays        = true # Alphabetically reorder array values that are not separated by blank lines.
+reorder_inline_tables = true # Alphabetically reorder inline tables.
+reorder_keys          = true # Alphabetically reorder keys that are not separated by blank lines.