[geezerjay]

Why should anyone force changes into the core language if all you want to do is use an obscure programming construct in a corner case that's easily implemented with a design pattern?

Some of these complains are at best very misguided.

[int_19h]

Have you considered that multiple dispatch is obscure because it requires jumping through such hoops to implement in most mainstream languages, rather than because of its lack of utility?

[kazinator]

The short answer is that the existence of multiple dispatch isn't motivated by the visitor pattern.

Moreover, multiple dispatch isn't obscure at all.

C++ has it, but only statically, for instance, in the form of overloaded functions. C++ chooses a function overload by looking at the types of all parameters and arguments.

Multiple dispatch is similar, but the run-time types of the arguments are used.

This is broadly applicable in making all sorts of situations nicer.

[bstamour]

Why have functions and control structures when we can just jmp?

[geezerjay]

That's a disingenuous comparison. Functions are used pervasively, but even the visitor pattern isn't used very often.

[bstamour]

But in languages that support multiple dispatch at the language level, they're just another way of writing polymorphic functions. They're not just a niche feature. When you don't have to write all of the ceremony of the visitor pattern, it's easier to use visitors everywhere without thinking about them.