adding a default.nix for nixpkgs

default.nix

@@ -0,0 +1,40 @@
+let
+  pkgs = import <nixpkgs> { };
+
+  customHaskellPackages = pkgs.haskellPackages.override {
+    overrides = self: super: {
+      mkDerivation = args: super.mkDerivation (args // {
+        jailbreak = true;  # Ignore version bounds
+        doCheck = false;   # Skip tests to avoid dependency issues
+      });
+    };
+  };
+in
+customHaskellPackages.mkDerivation {
+  pname = "dclock";
+  version = "0.1.0";
+
+  src = ./.;
+
+  isLibrary = false;
+  isExecutable = true;
+
+  executableHaskellDepends = with customHaskellPackages; [
+    base
+    QuickCheck
+    ansi-terminal
+    hspec
+    hspec-discover
+    lens
+    machines
+    optparse-applicative
+    text
+    time
+    process
+  ];
+
+  description = "A decimal clock that breaks your day into a 1000 decimal minutes";
+  license = pkgs.lib.licenses.mit;
+  maintainers = with pkgs.lib.maintainers; [ travgm ];
+  mainProgram = "dclock";
+}