But the point isn't that String#titlecase can't do the right thing here. I assume there is an implementation of titlecase that will work with ß. But I can't think of an Array#sum that will work for [1, "two"].
Of course your :) might have meant you were being funny, then I just totally missed your point and explained something you already know.
Well, there is a tenuous connection in that it's not obvious what to do for casing of ß. I wrote some unicode stuff for CL once and figuring this out was a nightmare. In any case, if you have two data types that that don't make any other sense as an addition, you could always just convert them both to bitfields and sum that... now I'm just being silly. Don't mind me.
Of course your :) might have meant you were being funny, then I just totally missed your point and explained something you already know.