The C++ type system is essentially a functional programming language, and it seems to have developed independently, indicating to me that there is something fundamental about functional programming. It turns out this has not just occurred to me and there is a deep relation between mathematical proof and functional expressions. Thus, if you are trying to prove anything logically, you will likely eventually end up with some kind of functional-looking notation or something that is very closely related.

For some reason, the moment you bring up mathematical thinking, most programmers shy away and claim that this isn't something they should work with 'everyday'.