WIP create ergonomic per-system flake helper

flake.nix

@@ -39,6 +39,20 @@
               ];
             } // builtins.removeAttrs args [ "modules" ]
           );
+        mkFlake = flakeDef:
+          let
+            rewritePerSystem = sectionDef: (forAllSystems (system:
+              builtins.mapAttrs (name: value:
+                nixpkgs.legacyPackages.${system}.callPackage value {}
+              ) sectionDef
+            ));
+          in
+            builtins.mapAttrs (name: value:
+              if name == "packages" || name == "legacyPackages" || name == "devShells" then
+                rewritePerSystem value
+              else
+                value
+            ) flakeDef;
       });
 
       legacyPackages = forAllSystems (system: