If you follow the rise and fall of programming languages-either from the comfort of an armchair, ensconced with your preferred tools but interested in other people's choices, or from a keyboard, happy to hyperkinetically try out all kinds of new idioms-you will have noticed an unmistakable trend in modern language design:a preference for static typing. Look at the major languages that have emerged in the past decade-Go, Swift, Kotlin, and Rust-they're all statically typed. Moreover, languages that were once dynamic have added static typing. The most conspicuous example is the recent set of updates to javascript (or more accurately, ECMAScript). Apple's choice to replace dynamically typed Objective-C with Swift also follows this trend.