Added custom lib (stolen from hlissner's dotifles)

lib/default.nix

@@ -0,0 +1,31 @@
+{ inputs, lib, pkgs, ... }:
+
+let
+  inherit (lib) makeExtensible attrValues foldr;
+  inherit (modules) mapModules;
+
+  # We define modules, so we can use mapModules
+  modules = import ./modules.nix {
+    inherit lib;
+    self.attrs = import ./attrs.nix { inherit lib; self = {}; };
+  };
+
+  # mylib = {
+  #   "attrs" = import "attrs.nix" { selg lib pkgs inputs };
+  #   "options" = import "options.nix" { selg lib pkgs inputs };
+  #   ...
+  #   "extend": <<lambda>>;    # from makeExtensible
+  #   "__unfix__": <<lambda>>; # from makeExtensible
+  #   }
+  mylib = makeExtensible (self:
+    with self; mapModules ./.
+      (file: import file { inherit self lib pkgs inputs; }));
+in
+# We have
+#   (attrValues super) = [ (import "attrs.nix" {...}) (import "options.nix" {...}) ... ]
+# And thus
+#   mylib.extend(...) = (import "attrs.nix" {...}) // (import "options.nix" {...}) // ...
+# Which is what we want, default.nix returns all modules merged (and extensible)
+mylib.extend
+  (self: super:
+    foldr (a: b: a // b) {} (attrValues super))