From 45dd7ec87849ff3dc1c2c14b2a910597671d9aeb Mon Sep 17 00:00:00 2001
From: figsoda <figsoda@pm.me>
Date: Wed, 22 Jul 2026 15:29:56 -0400
Subject: [PATCH] avoid copying nixpkgs to the store

---
 README.md              |  4 ++--
 src/__pathToString.nix | 15 +++++++++++++++
 src/callPackage.nix    |  2 +-
 src/crate2nix.nix      |  2 +-
 4 files changed, 19 insertions(+), 4 deletions(-)
 create mode 100644 src/__pathToString.nix

diff --git a/README.md b/README.md
index b847037..9f1f965 100644
--- a/README.md
+++ b/README.md
@@ -132,7 +132,7 @@ drowse.instantiate (finalAttrs: {
       version = "${finalAttrs.version}";
     }
   '';
-  env.NIX_PATH = "nixpkgs=${path}";
+  env.NIX_PATH = "nixpkgs=${nixpkgs}";
   dontUnpack = true;
 })
 ```
@@ -147,7 +147,7 @@ drowse.mkDynamicDerivation {
   version = "0.3.3";
 
   nativeBuildInputs = [ nix ];
-  env.NIX_PATH = "nixpkgs=${path}";
+  env.NIX_PATH = "nixpkgs=${nixpkgs}";
 
   buildCommand = ''
     drv=$(nix-instantiate --expr "(import <nixpkgs> { }).nix-init")
diff --git a/src/__pathToString.nix b/src/__pathToString.nix
new file mode 100644
index 0000000..102b74f
--- /dev/null
+++ b/src/__pathToString.nix
@@ -0,0 +1,15 @@
+# avoid copying stuff to the store when possible
+
+{ lib }:
+
+path:
+
+if !lib.isDerivation path && lib.isStorePath path then
+  let
+    str = toString path;
+  in
+  builtins.appendContext str {
+    ${str}.path = true;
+  }
+else
+  "${path}"
diff --git a/src/callPackage.nix b/src/callPackage.nix
index 14187b0..bc32f64 100644
--- a/src/callPackage.nix
+++ b/src/callPackage.nix
@@ -40,7 +40,7 @@ lib.extendMkDerivation {
       '';
 
       env = {
-        NIX_PATH = "nixpkgs=${path}";
+        NIX_PATH = "nixpkgs=${super.pathToString path}";
       }
       // env;
 
diff --git a/src/crate2nix.nix b/src/crate2nix.nix
index 2528960..f2097a7 100644
--- a/src/crate2nix.nix
+++ b/src/crate2nix.nix
@@ -73,7 +73,7 @@ lib.extendMkDerivation {
       '';
 
       env = {
-        NIX_PATH = "nixpkgs=${path}";
+        NIX_PATH = "nixpkgs=${super.pathToString path}";
       }
       // env;