nix: No need to pin the hash; git branch HEAD provides it

README.md

@@ -41,7 +41,7 @@ git add . && git commit -m rename
 
 ## Tips
 
-- Run `nix flake update` to update all flake inputs. nixpkgs is pinned to a specific a rev in `flake.nix`, which you can advance to the latest rev reported in [status.nixos.org](https://status.nixos.org).
+- Run `nix flake update` to update all flake inputs.
 - Run `treefmt` in nix shell to autoformat the project. This uses [treefmt](https://github.com/numtide/treefmt), which uses `./treefmt.toml` (where fourmolu and nixpkgs-fmt are specified).
 
 ## Alternatives

flake.lock

@@ -33,17 +33,17 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1651634615,
-        "narHash": "sha256-VtvcS61bLh5mIBm9cV3idUHdlfPRFus/NwdJfaj5s8o=",
+        "lastModified": 1651804312,
+        "narHash": "sha256-DJxOGlxwQccuuwXUS0oRRkcNJbW5UP4fpsL5ga9ZwYw=",
         "owner": "nixos",
         "repo": "nixpkgs",
-        "rev": "abfd31179174133ab8131139d650297bf4da63b7",
+        "rev": "d59dd43e49f24b58fe8d5ded38cbdf00c3da4dc2",
         "type": "github"
       },
       "original": {
         "owner": "nixos",
+        "ref": "nixpkgs-unstable",
         "repo": "nixpkgs",
-        "rev": "abfd31179174133ab8131139d650297bf4da63b7",
         "type": "github"
       }
     },

flake.nix

@@ -1,8 +1,7 @@
 {
   description = "haskell-template's description";
   inputs = {
-    # To find a suitable nixpkgs hash, pick one from https://status.nixos.org/ (these are cached)
-    nixpkgs.url = "github:nixos/nixpkgs/abfd31179174133ab8131139d650297bf4da63b7";
+    nixpkgs.url = "github:nixos/nixpkgs/nixpkgs-unstable";
     flake-utils.url = "github:numtide/flake-utils";
     flake-utils.inputs.nixpkgs.follows = "nixpkgs";
     flake-compat.url = "github:edolstra/flake-compat";