nimrod sdl example using iterators as continuations

sdlc.nim

import sdl, sdl_gfx

discard sdl.init(INIT_EVERYTHING)
var screen = setvideomode(800,600,16,SWSURFACE)

iterator checkEvent {.closure.} =
  var event_t: sdl.TEvent
  var event = addr event_t
  while true:
    if sdl.pollEvent(event) > 0:
      case event.kind
      of QUITEV:
        break
      of KEYDOWN:
        if evKeyboard(event).keysym.sym == K_ESCAPE:
          break
      else: nil
    
    yield

iterator update {.closure.} =
  while true: 
    yield
  
iterator draw {.closure.} =
  discard screen.fillrect(nil, 0xFFEEFF)
  while true: 
    discard screen.flip()
    
    yield

proc run =
  let tasks = [checkEvent, checkEvent, checkEvent, update, draw]
  var task = 0
  var t = tasks[task]
  while not finished(t):
    t()
    inc task
    t = tasks[task mod tasks.len]

run()