Add nixexprs

nixexprs/nixpkgs/default.nix

@@ -0,0 +1,22 @@
+{ overlays ? [ ] }:
+let
+  nixpkgs = builtins.fetchTarball {
+    url =
+      "https://github.com/ehmry/nixpkgs/archive/f8d0c5ee347a73ee7fa52b1f66f576fda793dfc4.tar.gz";
+  };
+in import nixpkgs {
+  overlays = [
+    (final: prev: {
+      ccacheWrapper = prev.ccacheWrapper.override {
+        extraConfig = ''
+          export CCACHE_DIR="/var/cache/ccache"
+          export CCACHE_UMASK=000
+        '';
+      };
+      nimPackages = prev.nimPackages.overrideScope' (final': prev': {
+        buildNimPackage =
+          prev'.buildNimPackage.override { stdenv = final.ccacheStdenv; };
+      });
+    })
+  ] ++ overlays;
+}