From 6889f53397edf4c2e94df67d72ef0b1e7b18d35a Mon Sep 17 00:00:00 2001
From: Profpatsch <mail@profpatsch.de>
Date: Sun, 26 Jun 2016 01:28:06 +0200
Subject: [PATCH 1/2] debug.nix: add traceSeq & traceValSeq

Debugging functions that strictly deep-evaluate the argument that should
be traced.
---
 lib/debug.nix | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/lib/debug.nix b/lib/debug.nix
index 2d10d981114..38612d630b3 100644
--- a/lib/debug.nix
+++ b/lib/debug.nix
@@ -19,6 +19,10 @@ rec {
   traceXMLVal = x: trace (builtins.toXML x) x;
   traceXMLValMarked = str: x: trace (str + builtins.toXML x) x;
 
+  # strict trace functions (traced structure is fully evaluated and printed)
+  traceSeq = x: y: trace (builtins.deepSeq x x) y;
+  traceValSeq = v: traceVal (builtins.deepSeq v v);
+
   # this can help debug your code as well - designed to not produce thousands of lines
   traceShowVal = x : trace (showVal x) x;
   traceShowValMarked = str: x: trace (str + showVal x) x;

From 93bbe13f98c1759330a6a37728607f636734b930 Mon Sep 17 00:00:00 2001
From: Profpatsch <mail@profpatsch.de>
Date: Sun, 26 Jun 2016 01:23:25 +0200
Subject: [PATCH 2/2] debug.nix: deprecate strict

Replace the implementation by seq and add a deprecation warning.
The semantics seems a little bit off, but the function should only be
used for debugging.
---
 lib/debug.nix | 24 +++---------------------
 1 file changed, 3 insertions(+), 21 deletions(-)

diff --git a/lib/debug.nix b/lib/debug.nix
index 38612d630b3..e2e895ab620 100644
--- a/lib/debug.nix
+++ b/lib/debug.nix
@@ -73,27 +73,9 @@ rec {
   # usage: { testX = allTrue [ true ]; }
   testAllTrue = expr : { inherit expr; expected = map (x: true) expr; };
 
-  # evaluate everything once so that errors will occur earlier
-  # hacky: traverse attrs by adding a dummy
-  # ignores functions (should this behavior change?) See strictf
-  #
-  # Note: This should be a primop! Something like seq of haskell would be nice to
-  # have as well. It's used fore debugging only anyway
-  strict = x :
-    let
-        traverse = x :
-          if isString x then true
-          else if isAttrs x then
-            if x ? outPath then true
-            else all id (mapAttrsFlatten (n: traverse) x)
-          else if isList x then
-            all id (map traverse x)
-          else if isBool x then true
-          else if isFunction x then true
-          else if isInt x then true
-          else if x == null then true
-          else true; # a (store) path?
-    in if traverse x then x else throw "else never reached";
+  strict = v:
+    trace "Warning: strict is deprecated and will be removed in the next release"
+      (builtins.seq v v);
 
   # example: (traceCallXml "myfun" id 3) will output something like
   # calling myfun arg 1: 3 result: 3