Are there any static duck-typed languages?

Question

Can I specify interfaces when I declare a member?

After thinking about this question for a while, it occurred to me that a static-duck-typed language might actually

Answer 1

New versions of C++ move in the direction of static duck typing. You can some day (today?) write something like this:

auto plus(auto x, auto y){
    return x+y;
}

and it would fail to compile if there's no matching function call for x+y.

As for your criticism:

A new "CallMyMethod" is created for each different type you pass to it, so it's not really type inference.

But it IS type inference (you can say foo(bar) where foo is a templated function), and has the same effect, except it's more time-efficient and takes more space in the compiled code.

Otherwise, you would have to look up the method during runtime. You'd have to find a name, then check that the name has a method with the right parameters.

Or you would have to store all that information about matching interfaces, and look into every class that matches an interface, then automatically add that interface.

In either case, that allows you to implicitly and accidentally break the class hierarchy, which is bad for a new feature because it goes against the habits of what programmers of C#/Java are used to. With C++ templates, you already know you're in a minefield (and they're also adding features ("concepts") to allow restrictions on template parameters).