On Sun, 17 May 2026 16:15:26 +0200, Volker Wysk wrote: > I have two mutually recursive predicates, which really need the tail > recursion optimisation. Does this [optimisation] also happen when > there are two or more predicates involved? I believe the answer is `yes' https://mercurylang.org/documentation/papers.html#tail_lopstr_lncs /Tomas