flake.nix provides pipewire paths through env

flake.nix

@@ -22,7 +22,7 @@
     # list directory contents as absolute paths
     lsAbsolute = with builtins;
       path:
-        map (name: toPath path + toPath name) (attrNames (readDir path));
+        map (name: (toPath path) + "/" + name) (attrNames (readDir path));
   in {
     overlays.default = final: prev: {
       dorne = final.haskellPackages.developPackage {
@@ -47,6 +47,7 @@
 
             # C Dependencies
             pipewire
+            pipewire.dev
 
             # Language/Development Tooling
             clang-tools
@@ -58,9 +59,24 @@
           shell = "${pkgs.bash}/bin/bash";
 
           # SPA API is provided by pipewire's "dev" derivation output
-          C_INCLUDE_PATH =
-            builtins.concatStringSep ":"
-            (lsAbsolute "${pkgs.pipewire.dev}/include");
+          NIX_CFLAGS_COMPILE = let
+            # libpipewire (and libspa)
+            Ipipewire =
+              lsAbsolute "${pkgs.pipewire.dev}/include";
+
+            Ivendor =
+              builtins.map
+              (x: "-isystem ${x}")
+              Ipipewire;
+          in
+            builtins.concatStringsSep " " ([
+                (builtins.getEnv
+                  "NIX_CFLAGS_COMPILE")
+              ]
+              ++ Ivendor);
+
+          DORNE_LDFLAGS = let
+          in "-L${pkgs.pipewire}/lib";
         };
       }
     );