Add mkAssert.

svn path=/nixpkgs/trunk/; revision=26600
2011-03-30 11:18:10 +00:00
parent 56ade5fef2
commit 11472a0501
1 changed files with 5 additions and 0 deletions
--- a/pkgs/lib/properties.nix
+++ b/pkgs/lib/properties.nix
@@ -223,6 +223,11 @@ rec {
      content = mkNotdef;
    };

+  mkAssert = assertion: message: content:
+    mkIf
+      (if assertion then true else throw "\nFailed assertion: ${message}")
+      content;
+
  # Remove all "If" statement defined on a value.
  rmIf = foldProperty (
      foldFilter isIf