Nil-safe accessors

[kengorab]

I'd like to be able to have a nil-safe accessor operator (?.) to access fields on Optional variables. If the variable is None, the entire rest of the expression is skipped and the result is None; if the value is not None, the next expression in the chain is evaluated. For example:

type Person {
  name: String
}

val people = [
  Person(name: "Ken")
]

people[0]?.name?.toLower() // "ken"

people[0]?.name.toLower()
               ^ Error, no field 'toLower' on String?

There should also be nil-safe accessors for indexing:

val arr = [[0], [1]]
arr[0]?.[1]

which should behave the same way; a None value would be chained along if ever present.