Lightweight API design in Swift
One of the most powerful aspects of Swift is just how much flexibility it gives us when it comes to how APIs can be designed. Not only does that flexibility enable us to define functions and types that are easier to understand and use — it also lets us create APIs that give a very lightweight first impression, while still progressively disclosing more power and complexity if needed.
Source: Lightweight API design in Swift, an article by John Sundell.