Why does Array{Int}() product Array{Int, 0} and not Array{Int, 1}

New to Julia
25

Union{Missing, T} is not 100% as fast as just using T, causes more allocations, and is not compatible with C code:

julia> struct Foo
       x::Int
       end

julia> struct FooM
       x::Union{Missing,Int}
       end

julia> function fillfoo(T,n)
       ret = Array{T}(undef, n)
       for k = 1:n
       ret[k] = T(1)
       ret
       end
       end

julia> @time fillfoo(Foo, 100000);
  0.046550 seconds (199.50 k allocations: 3.808 MiB)

julia> @time fillfoo(FooM, 100000);
  0.049624 seconds (299.50 k allocations: 8.385 MiB)