reduce.js

// a reduce function for a generator
// the result of the reducer function gets passed into next
function reduce(
  reducer,
  seed,
) {
  const gen = this(seed);
  let acc = seed;
  let results = [];
  let next = gen.next();
  while (!next.done) {
    results = [
      ...results,
      next.value,
    ];
    acc = reducer(
      acc,
      next.value,
    );
    next = gen.next(
      acc,
    );
  }
  return {
    acc,
    results,
  };
}

function* generate(param) {
  let _param = param;
  _param = yield _param + 1;
  _param = yield _param + 1;
  _param = yield _param + 1;
  _param = yield _param + 1;
  _param = yield _param + 1;
  return _param;
}

generate::reduce(
  (acc, val) =>
    acc + val,
  1,
)

// { acc: 63, results: [2, 4, 8, 16, 32] }