Allow applying custom functions during evaluation

scripts/Common/Scripts/eval-module.fish

@@ -6,6 +6,11 @@ function evalModule --argument-names modulePath property
         set -a argv --raw
     end
 
-    set -l nixPkgs 'import <nixpkgs> { config = {}; overlay = []; }'
-    nix eval --file "$modulePath" --apply "_: (($nixPkgs).lib.evalModules { modules = [ _ ]; }).config.$property" $argv
+    FILE=(realpath "$modulePath") \
+    PROPERTY="$property" \
+    nix eval \
+        --file "$(status dirname)/../../../lib/eval-module.nix" \
+        $argv
 end
+
+evalModule $argv