[boost] [Review] Proto review starts today, March 1st

Proto is the new backend for boost::spirit, boost::xpressive and the re-write of boost::phoenix, this is indeed an important library. It would seem that "Proto" already has the support of all of the top boost developers. 1) I wonder if you could give us a little bit of history, what motivated this library? 2) What were the defincies in previous design of boost::spirit. Why does spirit need a new backend? Learning to use boost:spirit is about a six month learing curve, but well worth it. For me, it was my introduction to functional programming. I'm excited to see what else is possible.