SE-0218 — Introduce compactMapValues to Dictionary

[Tino]

@Scott_James_Remnant

The Swift Dictionary type does not naturally work with Optional values*.

Adding an API surface with a "difficult" name to supplement an uncommon use case seems frivolous.

(* it's obviously possible, but there's no way with the natural subscript API to distinguish between a missing value and a nil one, amongst other Dictionary APIs)

Although I might well be the only one who voted against inclusion so far, I think your standpoint this is rather an argument for inclusion:
Due to how Optionals are modeled, they can be nested. I doubt that this is particular useful (but that's not up for debate), so if you read "does not naturally work with Optional values" as "try to avoid Optionals in Dictionaries", I agree.
As far as I understand it, this proposal is a way to avoid Dictionaries that contain Optionals - which you would create when using the existing map-function with a closure that returns an Optional.