How, the functions might support dynamic dispatch or be overloaded based on types.

There's nothing that prevents me from implementing all of

    plus(Int, Int)
    plus(Int, Vec)
    plus(Int, Mat)
    plus(Vec, Vec)
    plus(Vec, Mat)
    plus(Mat, Mat)

and to know which `plus` is being dispatched, you need to know the types of both arguments, exactly the same as if `plus` is named `__add__` in python or `operator+` in C++.