fn fromFn

Builds an iterator from a pull function: each call returns the next element or none at the end.

Example:

fn main() io {
  var n = 0
  let it = fromFn(() => {
    n += 1
    if n <= 3 { n * 10 } else { none }
  })
  print("{it.collect()}")
}

[10, 20, 30]

@intrinsic("iter.fromFn") pub(api) fn fromFn<T, effect F>(next: fn() -> T? F escaping) -> iter<T>  F

Complexity. O(1) to build; each pull calls `next` once.

Since. 1.0.0-beta

Parameters

Returns

iter<T> F

Effects

none declared (pure unless the body says otherwise)

Defined in: std/core/iter.oxl:27