Struggling with a Point type for several dimensions

New to Julia
4

I would add, having just found this out, I can’t use tuple. I need the elements of the point to be mutable. So I need to change x and y without destroying the point and creating a new one. So far hand rolled code looks like this, but I can’t use a linearAlgebra provided dot function, since it fails for tuple:

module point2D
    using LinearAlgebra
    export x, y, Point, dot
    mutable struct PointType{S}
#        x::Float64
#        y::Float64
        data::NTuple{S,Float64}
#        PointType{2}(x::Float64,y::Float64) = new{2}(x, y)
    end

    x(p::PointType{2}) = p.data[1]
    y(p::PointType{2}) = p.data[2]
    Point(x::Float64, y::Float64) = PointType{2}((x, y))
    Point() = PointType{2}((0.0, 0.0))
    function dot(u::PointType{2}, v::PointType{2})
        return u.data[1]*v.data[1] + u.data[2]*v.data[2]
    end

    x(p::PointType{3}) = p.data[1]
    y(p::PointType{3}) = p.data[2]
    z(p::PointType{3}) = p.data[3]

    Point(x::Float64, y::Float64, z::Float64) = PointType{3}((x, y, z))
    Point() = PointType{3}((0.0, 0.0, 0.0))

    # test code
    p1 = Point(1.0, 9.0)
    p2 = Point(5.0, 4.0)
    r = dot(p1, p2)
    println(r)
end

This is all academic now and back to the drawing board as I need to mutate the types within the point so tuple is out. I would like the above with an Array where I provide “S”. Can you help with that. I would like to not have to pay the price for a variable length array when I know the size is 2 or 3, but I’d like that type to be compatible with linAlg functions. Thoughts?

Thanks again,
Andy