Forgive what is probably and old discussion, but I am curious why array
subscripts create copies of arrays instead of views into them. Given
julia> a = [1:3 1:3];
I can mutate a whole column of the array in place by saying
julia> a[:,2] = [4:6];
julia> a
3x2 Array{Int64,2}:
1 4
2 5
3 6
But my sense of referential transparency is violated because I can't
further mutate that this way
julia> a[:,2][1] = 10;
julia> a
3x2 Array{Int64,2}:
1 4
2 5
3 6
I can achieve mutable sub-views with the sub function
julia> sub(a, :, 2)[1] = 10;
julia> a
3x2 Array{Int64,2}:
1 10
2 5
3 6
Why the difference? Why not make [] syntax sugar for sub? (As () will be
for call in 0.4)
