Always Write Functions to Cope with all Possible Parameter Values
Matt Galagher is back writing at Cocoa with Love. His goal is maintainability, which is the greatest of all, I think. It’s easy to copy code samples together to create an app, bur it’s hard to create a product you can keep alive and make better over years. In that vein, his first article, “Partial functions in Swift, Part 1: Avoidance”, includes a lot of details why partial functions will hurt you. This is a great topic. Read his post for the basic set theory involved.