[darklajid]

I don't quite understand the question. Are you asking if the latter example needs to modify the whole array, because you 'cut off' the first two elements?

I don't know J at all, but I'd assume that the result of the '{' is a _new_ array. All I've seen about J is very much rooted in mathematics and therefor I'd expect a functional/immutable language. Nothing would be 'deleted', no array changed/rearranged and a new array without the first two elements created/returned.

Note the fat 'no idea about J' disclaimer, of course.