# [−][src]Function core::iter::successors

ⓘImportant traits for Successors<T, F>

### Important traits for Successors<T, F>

`impl<T, F> Iterator for Successors<T, F> where
F: FnMut(&T) -> Option<T>, type Item = T;`

    pub fn successors<T, F>(first: Option<T>, succ: F) -> Successors<T, F> where
        F: FnMut(&T) -> Option<T>,

🔬 This is a nightly-only experimental API. (`iter_unfold` #55977)

Creates a new iterator where each successive item is computed based on the preceding one.

The iterator starts with the given first item (if any) and calls the given `FnMut(&T) -> Option<T>` closure to compute each item’s successor.

    #![feature(iter_unfold)]
    use std::iter::successors;

    let powers_of_10 = successors(Some(1_u16), |n| n.checked_mul(10));
    assert_eq!(powers_of_10.collect::<Vec<_>>(), &[1, 10, 100, 1_000, 10_000]);Run

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