* A new primop `builtins', which returns an attribute set containing

  all the primops.  This allows Nix expressions to test for new
  primops and take appropriate action if they're not available.  For
  instance, rather than calling a primop `foo' directly, they could
  say `if builtins ? foo then builtins.foo ... else ...'.

1 files changed, 12 insertions, 0 deletions

diff --git a/tests/lang/eval-okay-builtins.nix b/tests/lang/eval-okay-builtins.nix
new file mode 100644
index 000000000000..e9d65e88a817
--- /dev/null
+++ b/tests/lang/eval-okay-builtins.nix
@@ -0,0 +1,12 @@
+assert builtins ? currentSystem;
+assert !builtins ? __currentSystem;
+
+let {
+
+  x = if builtins ? dirOf then builtins.dirOf /foo/bar else "";
+
+  y = if builtins ? fnord then builtins.fnord "foo" else "";
+
+  body = x + y;
+  
+}