1 files changed, 16 insertions, 0 deletions
diff --git a/nix/sources-overlay.nix b/nix/sources-overlay.nix
new file mode 100644
index 0000000..b19bb34
--- /dev/null
+++ b/nix/sources-overlay.nix
@@ -0,0 +1,16 @@
+_: pkgs:
+
+rec {
+  pinnedDeps = builtins.attrNames
+    (builtins.removeAttrs pkgs.sources ["__functor"]);
+  overridePinnedDeps = builder: pkgs.lib.genAttrs pinnedDeps builder;
+
+  # Modifies a derivation with our source and version, keeping old build
+  # rules. This will fail if build steps have changed, or if no build
+  # rules are available upstream..
+  overrideSource = name: pkgs.${name}.overrideAttrs (old: old // rec {
+    name = "${name}-${version}";
+    version = pkgs.sources.${name}.version or pkgs.sources.${name}.rev;
+    src = pkgs.sources.${name};
+  });
+}