let's see how we go...

default.nix

@@ -0,0 +1,26 @@
+let
+  cfg = import ./nix/default.nix {};
+in
+{ pkgs ? cfg.pkgs }:
+
+  pkgs.stdenv.mkDerivation {
+    name = "my-site";
+    buildInputs = [
+      cfg.generator
+    ];
+    src = cfg.src;
+
+    # https://github.com/jaspervdj/hakyll/issues/614
+    # https://github.com/NixOS/nix/issues/318#issuecomment-52986702
+    # https://github.com/MaxDaten/brutal-recipes/blob/source/default.nix#L24
+    LOCALE_ARCHIVE = pkgs.lib.optionalString (pkgs.buildPlatform.libc == "glibc") "${pkgs.glibcLocales}/lib/locale/locale-archive";
+    LANG = "en_US.UTF-8";
+
+    buildPhase = ''
+      hakyll-site build
+    '';
+    installPhase = ''
+      mkdir -p "$out/dist"
+      cp -r ../dist/* "$out/dist"
+    '';
+  }