pkgs: import relative stockholm lib only once

New overlay code in inspired by <nixpkgs/pkgs/top-level/stage.nix>.

krebs/5pkgs/default.nix

@@ -1,17 +1,23 @@
-with import ../../lib;
+let
+  stockholm.lib = import ../../lib;
+in
+with stockholm.lib;
 self: super:
-
-# Import files and subdirectories like they are overlays.
-foldl' mergeAttrs {}
+fix (foldl' (flip extends) (self: super) (
+  [
+    (self: super: { inherit stockholm; })
+  ]
+  ++
   (map
-    (name: import (./. + "/${name}") self super)
+    (name: import (./. + "/${name}"))
     (filter
       (name: name != "default.nix" && !hasPrefix "." name)
       (attrNames (readDir ./.))))
-
-//
-
-{
-  brockman = self.haskellPackages.brockman;
-  reaktor2 = self.haskellPackages.reaktor2;
-}
+  ++
+  [
+    (self: super: {
+      brockman = self.haskellPackages.brockman;
+      reaktor2 = self.haskellPackages.reaktor2;
+    })
+  ]
+))

krebs/5pkgs/simple/default.nix

@@ -2,7 +2,7 @@ self: super:
 
 let
   # This callPackage will try to detect obsolete overrides.
-  lib = import ../../../lib;
+  lib = super.stockholm.lib;
   callPackage = path: args: let
     override = self.callPackage path args;
     upstream = lib.optionalAttrs (override ? "name")
@@ -13,5 +13,4 @@ let
     then lib.trace "Upstream `${upstream.name}' gets overridden by `${override.name}'." override
     else override;
 in
-  { stockholm.lib = lib; } //
-    lib.mapNixDir (path: callPackage path {}) ./.
+  lib.mapNixDir (path: callPackage path {}) ./.

krebs/default.nix

@@ -6,8 +6,8 @@
 
   nixpkgs = {
     overlays = [
-      (import ./5pkgs)
       (import ../submodules/nix-writers/pkgs)
+      (import ./5pkgs)
     ];
   };