From 77334757d7e3908b247bd3072d38d5d025f20e3a Mon Sep 17 00:00:00 2001
From: Eman Resu <78693624+quatquatt@users.noreply.github.com>
Date: Thu, 14 May 2026 19:28:43 -0400
Subject: [PATCH] lib.isFunction: save an attribute lookup

---
 lib/trivial.nix | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/lib/trivial.nix b/lib/trivial.nix
index fcd9a8791dcf..9a7305d500e1 100644
--- a/lib/trivial.nix
+++ b/lib/trivial.nix
@@ -1123,7 +1123,11 @@ in
     isFunction : Any -> Bool
     ```
   */
-  isFunction = f: builtins.isFunction f || (f ? __functor && isFunction (f.__functor f));
+  isFunction =
+    let
+      isFunction = builtins.isFunction;
+    in
+    f: isFunction f || (f ? __functor && isFunction (f.__functor f));
 
   /**
     `mirrorFunctionArgs f g` creates a new function `g'` with the same behavior as `g` (`g' x == g x`)