Arrays are covariant, and object is the base class of everything. I'm surprised that nobody's noticed that already (it's unsafe: arrays should instead be invariant).
It doesn't seem like there are any first class functions, and there's no tuple class either. I don't find any mention of mapping/selecting/reducing within standard collections.
For all (heh) the boasting about the type system, covariant arrays produce other problems too. If you have a function that takes an `Array[nullable Int]` and send it `Array[Int]`, the type system doesn't say anything about it. That means you could get into problems down the line. It's also possible to take a nullable Int and do `.as(Int)`
`var v = 1 / 0` causes FPE and core dump and dumps an ugly compiler stack trace.
The documentation about abort also mentions that there's no stack trace for it.
I don't think there are standalone functions with generic typing either, just classes with generic types. I suspect that their virtual types are probably unsound, but haven't tried working with them.