2022-06-24 04:47 GMT+10:00 "Volker Wysk" <post at volker-wysk.de>: > I've found it. It's defined in parsing.m. So "then" isn't a reserved word in > Mercury. This is one aspect of Mercury syntax that was inherited from Prolog. We have been fixing it, but only slowly; since it rarely causes any problems, it is not a priority. Zoltan.