That makes sense! It wasn't immediately obvious to me from the context of this discussion though, since it seemed like you were responding to the parent comment's framing of it as a choice between one or the other. This might just be from me never having heard of the term "unified call syntax" though, and I admit that I didn't expect to need to read through the PDF you linked before super carefully after opening it and seeing a bunch of C++-specific details that I knew would go over my head. (On a good day, I can remember what words SFINAE is an acronym for, but I don't think I ever really felt like I got comfortable enough with C++ to fully understand how the template code I saw actually encoded behavior that fit what I'd expect those words to mean).