@@ -1,5 +1,15 @@
1−# Nixpkgs with overlay
1+# Nixpkgs with Stackage overlay pinned to `nixpkgs.json` revision
22
3−{ nixpkgs ? import <nixpkgs> }:
3+{ pkgsPath ? null
4+, overlays ? []
5+, system ? null }:
46
5−nixpkgs { overlays = [ (import ./default.nix) ]; }
7+let
8+ _pkgs = import <nixpkgs> {};
9+ _pkgsPath = if pkgsPath != null
10+ then pkgsPath
11+ else _pkgs.fetchFromGitHub (_pkgs.lib.importJSON ./nixpkgs.json);
12+in
13+ import _pkgsPath ({
14+ overlays = [ (import ./default.nix) ] ++ overlays;
15+ } // (if system != null then { inherit system; } else {}))