/**
 * Returns the first event in this collection of events. If multiple events
 * occur in parallel and before any other events then any of these events
 * may be returned.
 *
 * @tsplus getter ParSeq first
 */
export function first<A>(self: ParSeq<A>): Maybe<A> {
  // eslint-disable-next-line no-constant-condition
  while (1) {
    switch (self._tag) {
      case "Single": {
        return Maybe.some(self.a)
      }
      case "Empty": {
        return Maybe.none
      }
      case "Both": {
        self = self.left
        break
      }
      case "Then": {
        self = self.left
        break
      }
    }
  }
  throw new Error("Bug")
}