Hi David, You probably haven't imported the parenscript package; try (ps:at a b) and see if that works. Regards, Jason On Wed, 2022-12-14 at 15:16 -0500, David O'Toole wrote: > Using the dot syntax for identifiers works (with a warning), but (@ a > b) and (getprop a b) don't work, the functions are undefined. What am > I doing wrong?