This is a direct demonstration that C++ is the right tool. Most good modern programming languages have sufficiently convenient syntax (in C++, function types,

This is a direct demonstration that C++ is the right tool. Most good modern programming languages have sufficiently convenient syntax (in C++, function types, templates and lambdas/closures) and sufficiently advanced libraries (like the set implementation the article relies on) to allow a functional programming style, which mostly means, like in the linked article, read-only data structures and higher order functions. For an established C++ or Python programmer, being able to "make one language do everything" is great and functional programming style is "the right tool" for some specific needs. Preferring certain "pure" languages for the purpose of doing functional programming, regardless of the domain, can be an interesting experiment but is completely backwards from a practical engineering point of view.