Yeah, I worry a bit about that too.  Having the consistency of aliases for all matchers seems desirable, but I do worry about the semi-insanity of this regex to support that.  In practice, I'm thinking that the predicate matchers may not be used that often in composable fashion, so maybe it's best not to provide aliases for them?  Users can always call `RSpec::Matchers.alias_matcher` to define their own aliases.  Thoughts?