To John Lam… you have the same type of inline syntax in PHP, and I’m sure a few dozen other languages. Ruby is great but that feature is far from unique.
Oh, and I think a sealed Strings class is great. There is nothing more annoying than having to maintain someone else’s code and seeing a class that you think you know how works but you don’t, because it’s a funky inherited type of a base system class and they’ve overridden half of it. Blench.