//
// Example 1
// Idealized event loop usage
//

// initialize state
while (event = get event) {
  switch (event.type) {
    case readable:
      // decide what read action is appropriate
      read (event.fd);
      // update state
      break;
    case writable:
      // decide what write action is appropriate
      write (event.fd);
      // update state
      break;
   }
 }

//
// Example 2
// Top-level driver loop for an event-driven programming library.
//

list<when, callback> timeouts;
callback fds[...];

// call amain() from main()
amain() {
  while(1){
    select() for fds[] and earliest timeout;
    for each readable fd
      cb = fds[selread][fd].
      cb()
    for each writable fd
      cb =fds[selwrite][fd];
      cb ();
    if a timeout has expired
      cb = timeouts.pop()
      cb()
  }
}

// register cb to be called when fd is ready for op (selread or selwrite)
// Set to NULL to clear
fdcb(fd, op, cb) {
  fds[op][fd] = cb;
}

// register cb to be called at specified time
delaycb(when, cb){
  timeouts.push(list(when, cb));
}