> Gosling: For me as a language designer, which I don't really count myself as these days, what "simple" really ended up meaning was could I expect J. Random Developer to hold the spec in his head. That definition says that, for instance, Java isn't -- and in fact a lot of these languages end up with a lot of corner cases, things that nobody really understands. Quiz any C developer about unsigned, and pretty soon you discover that almost no C developers actually understand what goes on with unsigned, what unsigned arithmetic is. Things like that made C complex. The language part of Java is, I think, pretty simple. The libraries you have to look up.[0]
So we can have this super powerful, extensible string interpolation system using never-before-seen syntax as a language feature, not a standard library extension, but not unsigned integers?
I'll echo what other commenters have said: This looks powerful but ugly. I'll add to it by pointing out that "powerful but ugly" is what we've already got. So we gain the ability to move format arguments inline with the string contents if we're willing to use the `STR."\{}"` syntax? That seems like a lateral move.