nix/tests/lang/eval-okay-builtins.nix
Eelco Dolstra 4a053bfdfd * 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 ...'.
2006-08-23 14:39:11 +00:00

13 lines
225 B
Nix

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;
}