feat: add transformInputs which allows initializing inputs

lib/core/builder.nix

@@ -10,6 +10,7 @@
     inputs,
     cellsFrom,
     cellBlocks,
+    transformInputs ? system: i: i,
     systems ? [
       "x86_64-linux"
       "aarch64-linux"
@@ -21,7 +22,7 @@
 
     loadOutputFor = system: let
       loadCell = createCellLoader {
-        inherit inputs system cells cellsFrom cellBlocks;
+        inherit inputs system cells cellsFrom cellBlocks transformInputs;
       };
 
       cells' = l.mapAttrsToList (cell: type: cell) (l.readDir cellsFrom);

lib/core/loader.nix

@@ -10,8 +10,9 @@
     inputs,
     system,
     cells,
+    transformInputs,
   }: let
-    importSignatureFor = createImportSignature {inherit inputs;};
+    importSignatureFor = createImportSignature {inherit inputs transformInputs;};
 
     loadCellBlock = cellName: cellP: cellBlock: let
       blockP = paths.cellBlockPath cellP cellBlock;
@@ -25,8 +26,8 @@
           then
             (callFlake (builtins.dirOf cellP.flake) {
               root = {
-                parent = inputs;
-                system = system;
+                parent = transformInputs system inputs;
+                inherit system;
               };
             }).outputs
           else {};
@@ -121,9 +122,10 @@
     cells,
     cellsFrom,
     cellBlocks,
+    transformInputs,
   }: let
     inherit (utils) unique accumulate;
-    loadCellBlock = createCellBlockLoader {inherit inputs system cells;};
+    loadCellBlock = createCellBlockLoader {inherit inputs system cells transformInputs;};
 
     loadCell = cellName: let
       cellP = paths.cellPath cellsFrom cellName;

lib/flake.nix

@@ -3,7 +3,8 @@
     nixpkgs-lib.url = "github:nix-community/nixpkgs.lib";
   };
 
-  outputs = inputs: import ./. {
-    inherit (inputs.nixpkgs-lib) lib;
-  };
+  outputs = inputs:
+    import ./. {
+      inherit (inputs.nixpkgs-lib) lib;
+    };
 }

lib/utils/import-signature.nix

@@ -22,12 +22,13 @@
         rev = cfg.inputs.self.sourceInfo.rev or "not-a-commit";
       };
   in {
-    inputs =
+    inputs = cfg.transformInputs system (
       (deSystemize system (cfg.inputs // additionalInputs))
       // {
         inherit self;
         cells = deSystemize system cells;
-      };
+      }
+    );
     inherit cell system;
   };
 in {