Move to generic subscripts in Swift 4

[lucianomarisi]

Since now generic subscripts have been introduced I think we should be aiming to move the API to them as this cleaner and simpler. For example:

let jsonDictionary: [String: Any] = ...
let value: String? = jsonDictionary[keyPath: "data.name"]

Would replace:

let jsonDictionary: [String: Any] = ...
let value: String? = jsonDictionary.json(atKeyPath: "data.name")

[Jon889]

Unfortunately subscripts can't throw yet :/

[lucianomarisi]

That's a shame, I was hoping this feature would be introduced Swift 4, maybe next year.