look at this simple function As I said, type-inferred languages do allow you to add type annotations when they are helpful. Note that your example has two arg

look at this simple function As I said, type-inferred languages do allow you to add type annotations when they are helpful. Note that your example has two arguments of the same type Array<Item>. In this case your even explicit typing doesn't prevent mixing up oldItems and newItems. In this case you want named parameters ...