The cognitive dissonance required to believe that C++ templates are 'monstrous' while Lisp S-expressions are awesomely useful and productive is enormous.

C++ templates are far from user-friendly, but they're literally (literally) just Lisp S-expressions with a Lisp syntax and semantics.

Short of writing your own DSL, how would you solve the problem the above code snippet is attempting to solve in C++?

I understand complaining about templates like the ranges example also posted in this thread, but I am curious to hear what you think is the alternative for this specific example.