I get where you are coming from, but it is obvious to me `forEach` is side effect because of its return type. Also I think `forEach` is great for cases such as

I get where you are coming from, but it is obvious to me `forEach` is side effect because of its return type. Also I think `forEach` is great for cases such as `arr.forEach(f)` where `arr: Array<T>, f: T => void`.