json2nix: add compiler as a package option

flake.nix

@@ -56,7 +56,8 @@
         # nix-packages-json = pkgs.emptyFile;
 
         # Internal Tools
-        json2nix = pkgs.callPackage ./internals/json2nix { };
+        json2nix =
+          pkgs.callPackage ./internals/json2nix { compiler = "ghc924"; };
       };
 
       overlays.default = _: prev: prev // self.packages.${system};

internals/json2nix/default.nix

@@ -1,7 +1,7 @@
-{ pkgs, ... }:
+{ pkgs, compiler ? "ghc924", ... }:
 let
-  overlayedPkgs = pkgs.extend
-    (pkgs.callPackage ./haskell-overlay.nix { compiler = "ghc924"; });
+  overlayedPkgs =
+    pkgs.extend (pkgs.callPackage ./haskell-overlay.nix { inherit compiler; });
 in overlayedPkgs.writers.writeHaskellBin "json2nix" {
   libraries = with overlayedPkgs.haskellPackages; [ aeson nixfmt extra text ];
 } (builtins.readFile ./json2nix.hs)