@thi.ng/transducers/symmetric.js

Collection of ~170 lightweight, composable transducers, reducers, generators, iterators for functional data transformations

function* symmetric(src) {
  let head = void 0;
  for (let x of src) {
    head = { x, n: head };
    yield x;
  }
  while (head) {
    yield head.x;
    head = head.n;
  }
}
export {
  symmetric
};