hasNoCompound

Whether this Clause is function-free in the Datalog sense: no argument, anywhere in the head or in any body literal, is a compound term (a Struct with Struct.arity > 0) — only constants and variables may appear as arguments. For instance parent(X, Y) qualifies, while parent(f(X), Y) does not, because f(X) is itself a compound. Backed by the CompoundFinder visitor.