From 1ff38bf6c69fd68cbf4e158a96cd8c97d6cf305d Mon Sep 17 00:00:00 2001
From: tv <tv@krebsco.de>
Date: Wed, 16 Mar 2016 01:17:07 +0100
Subject: [PATCH] krebs lib += optionalTrace

---
 krebs/4lib/default.nix | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/krebs/4lib/default.nix b/krebs/4lib/default.nix
index deac02bb7..e984614a0 100644
--- a/krebs/4lib/default.nix
+++ b/krebs/4lib/default.nix
@@ -17,7 +17,7 @@ let out = rec {
 
   types = import ./types.nix {
     inherit config;
-    lib = lib // { inherit genid; };
+    lib = lib // { inherit genid optionalTrace; };
   };
 
   dir.has-default-nix = path: pathExists (path + "/default.nix");
@@ -44,4 +44,6 @@ let out = rec {
   mapAttrValues = f: mapAttrs (_: f);
   setAttr = name: value: set: set // { ${name} = value; };
 
+  optionalTrace = c: msg: x: if c then trace msg x else x;
+
 }; in out