StructArrays + custom broadcasting + Makie

General Usage
3

Excellent, thanks! The thing I don’t understand is why Union{} is apparently “below” Foo but not Foo{Ta,Tb,Tc}:

julia> Union{} <: Foo
true

julia> Union{} <: Foo{Int64,Int64,Int64}
true

julia> Union{} <: Bool
true

julia>

Isn’t Union{} below everything, including concrete types?