From 7fae930a37a06fe08d4f85d6f41b04b37ed05cd0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Na=C3=AFm=20Favier?= <n@monade.li>
Date: Sat, 19 Mar 2022 20:39:52 +0100
Subject: [PATCH] lib/trivial: add warnIfNot and throwIf

Negated versions of warnIf and throwIfNot.
---
 lib/trivial.nix | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/lib/trivial.nix b/lib/trivial.nix
index c68bac902e91..fd0c9aba4fff 100644
--- a/lib/trivial.nix
+++ b/lib/trivial.nix
@@ -323,7 +323,14 @@ rec {
 
     Type: bool -> string -> a -> a
   */
-  warnIf = cond: msg: if cond then warn msg else id;
+  warnIf = cond: msg: if cond then warn msg else x: x;
+
+  /*
+    Like warnIf, but negated (warn if the first argument is `false`).
+
+    Type: bool -> string -> a -> a
+  */
+  warnIfNot = cond: msg: if cond then x: x else warn msg;
 
   /*
     Like the `assert b; e` expression, but with a custom error message and
@@ -347,6 +354,13 @@ rec {
   */
   throwIfNot = cond: msg: if cond then x: x else throw msg;
 
+  /*
+    Like throwIfNot, but negated (throw if the first argument is `true`).
+
+    Type: bool -> string -> a -> a
+  */
+  throwIf = cond: msg: if cond then throw msg else x: x;
+
   /* Check if the elements in a list are valid values from a enum, returning the identity function, or throwing an error message otherwise.
 
      Example: