iterators.cos

Function fn doubled(int[] nums) {
  mut int i = 0
  int? fn generator {
    int v = nums[i]?
    ++i
    if v is not void
      v * 2
  }
}

Function fn even(int[] nums) {
  int[] even_nums = nums->filter(&bool (int x): x % 2 == 0)
  mut int i = 0

  int? fn generator {
    int x = even_nums[i]?
    ++i
    x
  }
}

## 2, 4, 6, 8
every int n in doubled([1, 2, 3, 4])
  puts(n)

puts("") ## newline

## 2, 4, 6
every int n in even([1, 2, 3, 4, 5, 6])
  puts(n)