range.ms

# standard range func like in Python
range = fn(max)
  cur = 0
  f = fn()
    tmp = cur
    if cur >= max
      return
    (*f).cur = cur + 1
    return tmp
  return f

r = range(5)
print r() # 0
print r() # 1
print r() # 2
print r() # 3
print r() # 4
print r() # null - end of iterator
print '---'

# mutate closure environment
r.cur = 10
r.max = 13
print r() # 10
print r() # 11
print r() # 12
print r() # null - end of iterator