Simon Marlow wrote: > I vote for consistently using isXXXX for predicates. this would (only) affect "null" (maybe "isEmpty" again) and "member". Please omit at least "Of" from XxxxOf, or what was the intention of "Of"? In Map this leads to a name "isProperSubsetOfBy" and apart form this "Subset" should become "Submap" within Map! Christian