Hi Lawrence, thanks for the reply. In this case, Immutable refers to a particular library released by Facebook called Immutable.js. If you use my ImmutableVirtualizedList component, it expects data created by Immutable.js (e.g. Immutable.List([1, 2, 3])).

Indeed, a brand new list will be created each time you add new data, but their library has optimizations that make this extremely efficient; I recommend reading through their home page to learn more. I hope that helps.