Which lisps? I think I have only ever seen that in clojure (thinking it was a bad idea), and clojure seems scared of parentheses. (not (equal? x y z)) is clearer, but suffers from the same drawback as your question.
The problem I think is that not= returns true as long as any elements are non-equal, which means it is not analogous to +. I can't speak for clojure, but this is in line with all equality predicates in scheme, negated or not. A predicate that checked if any neighbours are not equal would in true scheme spirit probably be called not-any-neighbour-equal? :)
The problem I think is that not= returns true as long as any elements are non-equal, which means it is not analogous to +. I can't speak for clojure, but this is in line with all equality predicates in scheme, negated or not. A predicate that checked if any neighbours are not equal would in true scheme spirit probably be called not-any-neighbour-equal? :)