The abbreviated Function Templates

How to write abbreviated function templates

There is no need for any template parameter list or requires clause when we use abbreviated function templates. We can directly use the concept where the function arguments are enumerated.

auto add(Number auto a, Number auto b) {
  return a+b;
}

Note that after the concept Number we put auto. As such, we can see that Number is a constraint on the type, not a type itself. Imagine if we saw auto add(Number a, Number b). As users, how would we know that Number is not a type, but a concept?

Another thing to note is that, when we use the abbreviated function template, we can mix the types of parameters. We can add an int to a float.