It can be syntactic sugar in terms of how it's defined, but the implementation can still be smart and use a compact representation where possible (this is basic

It can be syntactic sugar in terms of how it's defined, but the implementation can still be smart and use a compact representation where possible (this is basically RLE). Similarly, if you have tuples (or structs with anon fields etc) in the language, you could unify those with arrays such that struct { int; int; } is the same as int[2].