Set up Nix LSP and auto-formatting in VSCode

.vscode/extensions.json

@@ -0,0 +1,7 @@
+{
+    "recommendations": [
+        "jeff-hykin.better-nix-syntax",
+        "pinage404.nix-extension-pack",
+        "mkhl.direnv"
+    ]
+}

.vscode/settings.json

@@ -0,0 +1,14 @@
+{
+    "nix.enableLanguageServer": true,
+    "nix.formatterPath": "nixpkgs-fmt",
+    "nix.serverSettings": {
+        "nil": {
+            "formatting": {
+                "command": [
+                    "nixpkgs-fmt"
+                ],
+            }
+        }
+    },
+    "direnv.restart.automatic": true,
+}

flake.lock

@@ -169,6 +169,32 @@
         "type": "github"
       }
     },
+    "nil": {
+      "inputs": {
+        "flake-utils": [
+          "nixvim",
+          "devshell",
+          "flake-utils"
+        ],
+        "nixpkgs": [
+          "nixpkgs"
+        ],
+        "rust-overlay": "rust-overlay"
+      },
+      "locked": {
+        "lastModified": 1717086091,
+        "narHash": "sha256-GmsEQa4HZeMfec37LZnwG/Lt/XmqFLXsjv5QWojeNiM=",
+        "owner": "oxalica",
+        "repo": "nil",
+        "rev": "ab3ddb8f063774cf7e22eb610f5ecfdb77309f3c",
+        "type": "github"
+      },
+      "original": {
+        "owner": "oxalica",
+        "repo": "nil",
+        "type": "github"
+      }
+    },
     "nix-darwin": {
       "inputs": {
         "nixpkgs": [
@@ -293,6 +319,7 @@
         "_1password-shell-plugins": "_1password-shell-plugins",
         "flake-parts": "flake-parts",
         "home-manager": "home-manager",
+        "nil": "nil",
         "nix-darwin": "nix-darwin",
         "nix-index-database": "nix-index-database",
         "nixos-flake": "nixos-flake",
@@ -301,6 +328,31 @@
         "treefmt-nix": "treefmt-nix"
       }
     },
+    "rust-overlay": {
+      "inputs": {
+        "flake-utils": [
+          "nil",
+          "flake-utils"
+        ],
+        "nixpkgs": [
+          "nil",
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1717035469,
+        "narHash": "sha256-MzH+yjKULH3HCRj9QCTwBvqq4LZkR0ZqRE/QfGOGC2E=",
+        "owner": "oxalica",
+        "repo": "rust-overlay",
+        "rev": "095702e63a40e86f339d11864da9dc965b70a01e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "oxalica",
+        "repo": "rust-overlay",
+        "type": "github"
+      }
+    },
     "systems": {
       "locked": {
         "lastModified": 1681028828,

flake.nix

@@ -36,6 +36,12 @@
 
     treefmt-nix.url = "github:numtide/treefmt-nix";
     treefmt-nix.inputs.nixpkgs.follows = "nixpkgs";
+
+    nil = {
+      url = "github:oxalica/nil";
+      inputs.nixpkgs.follows = "nixpkgs";
+      inputs.flake-utils.follows = "nixvim/devshell/flake-utils";
+    };
   };
 
   outputs = inputs@{ self, ... }:
@@ -383,6 +389,14 @@
             treefmt.config = {
               projectRootFile = "flake.lock";
               programs.nixpkgs-fmt.enable = true;
+              programs.nixpkgs-fmt.package = pkgs.nixpkgs-fmt;
+            };
+
+            devShells.default = pkgs.mkShell {
+              nativeBuildInputs = with pkgs; [
+                inputs.nil.packages.${system}.nil
+                nixpkgs-fmt
+              ];
             };
           };
         }