Add flake support

.envrc

@@ -1 +1 @@
-use nix
+use flake

flake.lock

@@ -0,0 +1,43 @@
+{
+  "nodes": {
+    "flake-utils": {
+      "locked": {
+        "lastModified": 1667395993,
+        "narHash": "sha256-nuEHfE/LcWyuSWnS8t12N1wc105Qtau+/OdUAjtQ0rA=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "5aed5285a952e0b949eb3ba02c12fa4fcfef535f",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1670064435,
+        "narHash": "sha256-+ELoY30UN+Pl3Yn7RWRPabykwebsVK/kYE9JsIsUMxQ=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "61a8a98e6d557e6dd7ed0cdb54c3a3e3bbc5e25c",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "flake-utils": "flake-utils",
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

@@ -0,0 +1,19 @@
+{
+  description = "Build my xmonad config";
+
+  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+  inputs.flake-utils.url = "github:numtide/flake-utils";
+
+  outputs = { self, nixpkgs, flake-utils }:
+
+    flake-utils.lib.eachDefaultSystem (system:
+      let pkgs = nixpkgs.legacyPackages.${system}; in
+      {
+        devShells.default = import ./shell.nix { inherit pkgs; };
+      }) // {
+    packages.x86_64-linux.default =
+      # Notice the reference to nixpkgs here.
+      with import nixpkgs { system = "x86_64-linux"; };
+      haskellPackages.callCabal2nix "xmonad-config" ./. {};
+  };
+}

shell.nix

@@ -1,4 +1,4 @@
-{ pkgs ? import <nixpkgs> { } }:
+{ pkgs }:
 let
   inherit (pkgs) callPackage fetchFromGitHub mkShell;
   easy-hls-src = fetchFromGitHub {