pub fn unfold<F, S, A>(value: S, f: F) -> Unfold<F, S>ⓘNotable traits for Unfold<F, S>impl<F, S, A> Iterator for Unfold<F, S> where
F: Fn(&S) -> Option<(A, S)>, type Item = A; where
F: Fn(&S) -> Option<(A, S)>, Expand description
Create an iterator of values using a function to update a state value.
The function is called with the current state as its argument, and
should return an Option of a tuple of the
next value to yield from the iterator and the updated state. If
the function returns None, the
iterator ends.
Examples
// Create an infinite stream of numbers, starting at 0.
let mut it = unfold(0, |i| Some((*i, *i + 1)));
// Make a list out of its first five elements.
let numbers = Vector::from_iter(it.take(5));
assert_eq!(numbers, vector![0, 1, 2, 3, 4]);