Creates a new closure that returns an iterator where each iteration steps the given generator to the next yield statement.

Similar to iter::from_fn, but allows arbitrary control flow.

Examples

#![feature(iter_macro, coroutines)]

let it = std::iter::iter!{|| {
    yield 1;
    yield 2;
    yield 3;
} }();
let v: Vec<_> = it.collect();
assert_eq!(v, [1, 2, 3]);