[Pitch] `With` functions in the standard library

Evolution Pitches
115

Assuming that the pack iteration pitch turns into an accepted proposal (and I understood the syntax well :sweat_smile:), I think .with could be composed with a function like the following:

func setting<Root, each Value>(_ keyPathAndNewValue: repeat (WritableKeyPath<Root, each Value>, each Value)) -> (inout Root) -> Void {
  { value in
    for keyPath, newValue in repeat (each keyPathAndNewValue) {
      value[keyPath: keyPath] = newValue
    }
  }
}

to enforce simple setting or properties with no closure via key paths, so something like:

let components = another.with(setting(
  (\.path, "foo"),
  (\.password, "bar")
))