Personally, on one hand I know allowing computations into configuration immediatly destroys any hope of having a tidy, rational schema in real word projects.
On the other hand though, i do believe configuration and code should be build with related tools, possibly the same tool- or at least tools using the same syntax!
(a bit like the json syntax is the same as a Python dict syntax, except this is the terrible example that is so poorly thought out that does more harm than good)
This unlocks a much greater degree of freedom and power than all the gluing together technologies that we have to do...