Haskell's `iterate` in Javascript

Haskell’s iterate accepts a function f and an arugment x, and produces an infinite list of repeated application of f to x.

iterate f x == [x, f x, f (f x), ...]

It’s handy for recursion.

With ES6’s Generators, this is can be easily implemented in Javascript.

function* iterate(f, x) {
  yield x;
  while (true) {
    x = yield f(x);
  }
}

If a takeWhile is implemented alongside, then we have something that takes a predicate for the base case of the recursion.