I'm certainly glad if MessagePack allows non-string keys in maps, as it apparently does (I've only read the spec so far, but not had a chance to try the code). This is a real pain in JSON.

My stock “basic data type” set comes mainly from Ruby these days. I wince a little at the lack of interned-symbol type, but it's possible to live without that. But what of string encodings? In a recent piece of code which I wouldn't mind replacing with MessagePack, I prefix strings with fixnum IANA encoding numbers. I suppose that's too much to ask in this context, though… ? How do other people deal with this—just force everything to UTF-8?