ProductArrays

productArray(vectors...)

The output is a lazy form of

collect(Iterators.product(vectors...))

i.e. it is an AbstractArray in contrast to Iterators.product(vectors...). So is accessible with getindex and gets default Array implementations for free. In particular it can be passed to Base.PermutedDimsArray for lazy permutation and vec() to obtain a lazy Base.ReshapedArray.

Examples:

julia> A = productArray(1:3, (:a,:b))
3×2 ProductArrays.ProductArray{Tuple{UnitRange{Int64}, Tuple{Symbol, Symbol}}, Tuple{Int64, Symbol}, 2}:
 (1, :a)  (1, :b)
 (2, :a)  (2, :b)
 (3, :a)  (3, :b)

julia> vec(A)
6-element reshape(::ProductArrays.ProductArray{Tuple{UnitRange{Int64}, Tuple{Symbol, Symbol}}, Tuple{Int64, Symbol}, 2}, 6) with eltype Tuple{Int64, Symbol}:
 (1, :a)
 (2, :a)
 (3, :a)
 (1, :b)
 (2, :b)
 (3, :b)

julia> sizeof(A) == sizeof(1:3) + sizeof((:a,:b))
true

julia> A == collect(Iterators.product(1:3, (:a,:b)))
true