I believe there is a lot of room for improvement in array accesses. For example:

- Better reasoning about array properties (e.g. an Integer[] must be flat).
- I notice there are times when the strategy to do a type assert of the array fails and we have to go through the full series of type check.
- Better profiling, it should answer the questions: has a flat array been observed, has a non-flat array been observed, etc.