Something I really like about Scheme is how mutators are generally suffixed with an exclamation point and predicates with a question mark. For example: (nul

Something I really like about Scheme is how mutators are generally suffixed with an exclamation point and predicates with a question mark. For example: (null? spotted-ufos) (vector-set! drakes 0 maui-mallard) Having a simple and clear convention like that is something I consider good design.