Simple suspend implementation

package.json

{"type": "module"}

suspend.js

function suspend(gen) {
  function next(result){
    if(result.done){
      return result.value
    } else {
      if(result.value instanceof Promise) {
        return result.value.then(
          value => next(gen.next(value)),
          error => next(gen.throw(error)),
        )
      } else {
        return next(gen.next(result.value))
      }
    }
  }
  return next(gen.next())
}

const x = await suspend(function*() {
  const x = yield Promise.resolve(1)
  console.log('x', x)
  try {
    yield Promise.reject('error!')
  } catch(e) {
    console.log('error caugh', e)
  }
  const timeout = yield new Promise(res => setTimeout(() => res('timeout!'), 1000))
  console.log(timeout)
  return x
}())

console.log('finally x is', x)