Iterators

For

Iteration goes through the for loop:

for (item : items) {
  @println("{}", item);
}

Iterable Types

Type	Yields
integers	numbers
ranges	numbers
[N]T, []T	elements
struct with Iterator	next() values

Containers like List iterate through .iter():

---

for (x : items.iter()) {}

Custom Iterators

A type iterates by implementing Iterator: next returns Some(element) or None when done.

struct Counter {
  cur: i32,
  end: i32,

  pub fn until(end: i32) Self {
    Self { .cur = 0, .end = end }
  }
}

implement Iterator : Counter {
  fn next(*self) Option[i32] {
    if (self.cur < self.end) {
      let output = self.cur;
      self.cur += 1;

      return Option.Some(output);
    }

    Option.None
  }
}

fn main() {
  let counter = Counter.until(5);

  for (i : counter) {
    @println("{}", i);
  }
}