Don't use examples without explaining what they are an example of.
Could you give an example? No snark, I just don't know exactly what you're referring to here.
https://tzlaine.github.io/yap/doc/html/boost_yap__proposed_/manual/tutorial/... "Let's see an expression template type with some operators:" OK I see it, but I don't understand what you want me to be looking at. There is only one operator (with some caveat) and two macros that could well be operators. But to be honest, I just looked and didn't find many more cases. I think you can chalk this up to the general request for the tutorial: slow down and introduce more.
*Section Dependencies Why depend on Hana, my impression of Hana and the associated review / discussion is that this library is made for demonstration of next generation C++ rather than actual use.
Because it makes everything having to do with tuple use and manipulation easy. This is why we make and use libraries, right? So we don't each have to reinvent the wheel?
That could be right. However, to me it seems that you chose quite an esoteric template class for the public interface.