fix: root module use module design pattern

nib/default.nix

@@ -1,8 +1,20 @@
 {systems, ...}: let
-  std = import ./std;
+  std = import ./std {};
+  parse = import ./parse {
+    attrs = std.attrs;
+    result = std.result;
+  };
 in
+  builtins.listToAttrs [
+    # submodule content is accessible first by submodule name
+    # then by the name of the content (ie self.submodule.myFunc)
+    {inherit parse;}
+
+    # submodule is included directly to this module (ie self.myFunc)
     std
-  // {
+
+    # this module
+    {
       # === External Functions ===
       withPkgs = repo: config: system:
         import repo {
@@ -10,17 +22,27 @@ in
         }
         // config;
 
-    mkSys = input: {
+      mkSys = input: let
+        # function taking a system as argument
+        pkgsFor = input.pkgs;
+      in {
+        inherit pkgsFor;
         forAllSystems = f:
           std.genAttrs systems (
-          system: f system input.pkgs
+            system: f system (pkgsFor system)
           );
       };
 
-    mkUSys = input: {
+      mkUSys = input: let
+        # functions taking a system as argument
+        pkgsFor = input.pkgs;
+        upkgsFor = input.upkgs;
+      in {
+        inherit pkgsFor upkgsFor;
         forAllSystems = f:
           std.genAttrs systems (
-          system: f system input.pkgs input.upkgs
+            system: f system (pkgsFor system) (upkgsFor system)
           );
       };
     }
+  ]