Parametric Type for Uninitialized/Undef Objects

I’ve learned that you can create type-stable references to uninitialized objects like so:

julia> struct Foo{A} a::A end

julia> x = Ref{Foo{Int}}()

julia> x[] = Foo(1)

julia> y = Array{Foo{Int}}(undef)
0-dimensional Array{Foo{Int64}, 0}:

julia> y[] = Foo(1)

I have a function which receives a wide range of possible argument types (including types).

I’d like a way to communicate to this function the type of an uninitialized object to make a reference to, in a way that simultaneously communicates that a reference to an uninitialized object should be created (i.e., when simply sending normal types I want it not to behave this way), and without forcing the other arguments to also be uninitialized.

I’m thinking maybe something similar to Val(Foo{Int}), but not using Val because that usually means something different. Something along the lines of maybe Undef(Foo{Int}), if it worked like Undef(Foo{Int}) === Undef{Foo{Int}}()?

I imagine if Ref’s constructor had a type-specialization for it, such a thing could work like this:

#= simulated =#
julia> Ref(Undef(Foo{Int}))

or that you could initialize an array like so:

#= simulated =#
julia> Matrix(Undef(Int), 4, 4)
4×4 Matrix{Int64}:
 1847054304048  1847054304816  1847054305072  1847054306160
 1847054304624  1847054304880  1847054305328  1847054306224
 1847054304688  1847054304944  1847054306032  1847054306288
 1847054304752  1847054305008  1847054306096  1847054306352

Is there any existing type that’s suitable for this?