a = Array{Int}[]
push!(a, [1 2; 3 4])
@show typeof(a)
Array{Array{Int64,N} where N,1}
In the above, how should I read where N,1? Especially, what does 1 represent here?
How may I create a variable of type Array{Array{Int64,N} where N,2}?
actually, the 1 goes with the outermost Array, the meaning of this type is:
“Array of 1 dimension, and element of this array is of type Array{Int64, N}”,
the where N means N is not specified, such that it is possible to push vector or even a higher dimensional tensor into a:
julia> push!(a, rand(Bool, 2,2,2))
2-element Vector{Array{Int64, N} where N}:
julia> a[1]
2Ă—2 Matrix{Int64}:
julia> a[2]
2Ă—2Ă—2 Array{Int64, 3}:
Maybe this will also help you understand:
julia> [[1 2;3 4]]
1-element Vector{Matrix{Int64}}:
julia> Matrix{Int64} == Array{Int64,2}
true
The reason why your original example didn’t return a
Array{Matrix{Int64}, 1}
is because you specifically wanted the flexibility in N:
julia> Array{Int}
Array{Int64, N} where N
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Ah! Thanks. Makes sense. Can’t believe I couldn’t catch it 
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