Compile time is the most efficient way (IMO) to deal with all the types that can appear (also in intermediate steps of a calculation). I found this idea first realized in this implementation: https://github.com/JaapSuter/Vital. According to the comments in the code is from 2004 so it did could not make use of C++0x, which is why I adopted it rewrote it for C++11. This was motivated by an actual problem I had to solve but, sadly, it turned out GA isn't fit for it.