Here is a related link that is relevant to D:
https://stat.ethz.ch/pipermail/r-sig-mixed-models/attachments/20131209/ec911711/attachment.pl
It's an announcement that he's moving to Julia, but part of the
problem is
"Eigen is a complex code base using what is called "template
meta-programming" in C++. Making modifications to such code can
be
difficult. I can't claim to fully understand all the details in
Eigen and
in Rcpp. I am a user of these code bases, not a developer."
That's my experience as well. C++ is fine for simple things, but
once you cross the line from simple to intermediate, all hell
breaks loose. D is IMO a much better choice for working with R
because it's possible to understand what is going on inside the D
code even if you have less than 10 years of D programming
experience.
