An array will carry type information for each element. Link looks like an optimized array which only allows three types so it can more efficiently pack the typ

An array will carry type information for each element. Link looks like an optimized array which only allows three types so it can more efficiently pack the type (and presence) information for a block of items into a a couple of words. Plus it doesn’t hold references so managing its lifetime is simple, and you get cheap concatenation by chaining blocks. I’d guess it’s good for lookup tables or large indexes.