Very good article. If you think about it, you will see this pattern in many places. Simply because it is the outcome of emphasizing pure functions. For example

Very good article. If you think about it, you will see this pattern in many places. Simply because it is the outcome of emphasizing pure functions. For example, it's the heart of the virtual DOM in React. Pure functions create an entirely new (no mutation) virtual DOM, and then something at the "impure boundary" applies this to the actual, messy, mutable DOM of the browser. With a little thought you can probably find several other well-known examples.